Broad market demand and high profits promote the rapid development of small household appliances industry, production lines have been throughout the rice cooker, induction cooker, electric frying pan, hair dryer and electric kettle, small household appliances have become the necessity of today’s families. The vast majority of small household appliances are working in high temperature environment, in order to better protect its various working parts, the coating also put forward the basic performance of high temperature and wear resistance. At the same time better decorative and other performance can better meet the market demand.
One, silicone coating
Silicone coating is one of the earliest and most widely used high-temperature resistant coatings for small household appliances in China. Silicone coating is mainly composed of silicone resin as the main component, silicone resin shows a complex network staggered structure, stable chemical properties, good high temperature resistance. The working temperature of most small household appliances is usually below 300℃, and the highest temperature resistance of silicone coating can also reach 300℃. From the perspective of temperature resistance performance, silicone coating is a very suitable high-temperature coating for small household appliances.
In order to meet the needs of a few small home appliance working temperature over 300 ℃, paint manufacturers of organic silicon coating modification, the basic principle of modification is to reduce the not high temperature resistant ingredients such as hydroxyl content, increased Si – O – Si keys and the proportion of high temperature resistant inorganic components, combined with modern advanced composite materials processing technology, The high temperature resistance of silicone coating is significantly improved, even up to 600℃.
Silicone coating not only has good high temperature resistance, but also has strong adhesion, high coating hardness, simple process and low cost. These advantages make silicone coating shine in the domestic small household appliance market and favored by small household appliance enterprises. But the shortcomings of silicone coating are also obvious, mainly in the following aspects:
(1) backsticking phenomenon. The coating prepared by silicone coating is intensified in molecular thermal motion at high temperature, and the structure will soften. When contacting with sharp objects, the silicone coating attached to the surface of small household appliances is prone to scratches and other damage to the coating phenomenon.
(2) Security issues. There are some toxic ingredients in the silicone coating, which will gradually spread from the inside to the surface through infiltration, especially the coating directly in contact with food, there may be food safety hazards;
(3) Ultra-high temperature resistance. With the further improvement of the use temperature of some household appliances, the working temperature of small household appliances even reaches 600℃, how to further improve the use temperature of silicone coating has become an urgent problem to be solved. At present, a small number of large silicone coating manufacturers with r&d strength are conducting relevant research and have made some progress, but there is still a long way to go from practical application.
Two, fluorocarbon coating
Fluorocarbon coating, as a new material, has not been applied for a long time at home and abroad, but its excellent high-temperature resistance, strong corrosion resistance, self-cleaning, strong adhesion and super weather resistance have been widely concerned. Fluorocarbon coating is the main component of fluorine resin, its chemical properties are very stable, excellent high temperature resistance. Small household appliances coated with fluorocarbon coating can continue to be used in the environment of 260℃ without change, and fluorocarbon coating is insoluble in oil, will not react with food, good safety. The advantages of fluorocarbon coating are obvious, but the disadvantages are also very prominent. Its shortcomings are mainly manifested in its own temperature resistance, hardness and construction of three aspects. The hardness of fluorocarbon coating at normal temperature is only 2-3h, that is to say, fluorocarbon coating at normal temperature does not need a shovel, steel wire brush, or even just with fingernails can be scratched fluorocarbon coating, such as the fluorocarbon coating used in electric irons encounter buttons and other sharp objects often appear scratches damage coating phenomenon. Fluorocarbon coatings can work stably in an environment of 260℃, and tend to melt when the temperature is higher than this. The low hardness of fluorocarbon coating determines the difficulty of fluorocarbon coating in construction and technological conditions. How to keep the adhesion and smoothness of fluorocarbon coating in the bonding process is particularly important. Future development direction of high quality fluorocarbon coating:
(1) Solve the current solvent-based high temperature resistance, hardness and harsh construction conditions and other problems;
(2) green environmental protection water-based fluorocarbon coating;
(3) Composite of nanomaterials and fluorocarbon coatings to improve the coating density and other comprehensive properties.
Three, powder coating
Powder coatings have been widely recognized as “Efficiency, deep, Ecology and Economy” coatings due to their advantages of no organic solvent, no pollution, high utilization rate and low energy consumption. Powder coatings can be divided into thermoplastic powder coatings and thermosetting powder coatings according to different film forming substances. What small home appliance uses normally is heat solid model powder coating, its principle is to use the resin with small molecular weight and curing agent to produce cross linking reaction to form reticulate macromolecule coating in high temperature action. In the field of small household appliances, polyester powder coating, acrylic powder coating, epoxy powder coating and polyurethane powder coating are more widely used. Powder coatings have developed rapidly in recent years, with more and more kinds and better performance. The use cost of powder coating is still very high for small household appliances with relatively low cost. It is hoped that coating manufacturers can develop low cost and high performance powder coating suitable for small household appliances.
Ultraviolet light (UV) curing coating also appeared on the market at present, its principle is to use ultraviolet light to induce photoinitiator to make photosensitive resin unsaturated key group cross-linking reaction to form the structure of the coating. Although the production process of uV-curable coating is simple, it is expensive and the thermal stability of coating is not ideal, so it cannot be widely used in the production of small household appliances.
Post time: Mar-15-2022