It can be seen from the archaeological data that the use of paint has been nearly 10000 years since the Stone Age, the Bronze Age and the Iron Age. The adhesives used for coatings have also developed from the original animal oil and natural plant juice to today's modified natural oils, natural resins and synthetic organic high molecular polymers. Its application has also evolved from the original rock painting to architecture, handicrafts, agriculture, shipbuilding and even today's various fields. Whether it is a thousand-year-old paint or a latex paint with a history of more than 60 years, it has become an independent paint chemical industry with many varieties and complete functions. The decorative, protective, functional and special effects of coatings are fully and continuously playing a role.
The global total annual production of coatings is estimated at 120 million to 150 million tons, of which architectural coatings account for about 30% to 40%. Apart from industrial paint, there are two major categories of architectural paint: solvent paint and latex paint. Except for pigments and fillers, almost all the components of solvent based architectural coatings are organic compounds; Due to different varieties, organic compounds account for 40% to 100% of the paint quality. The composition of emulsion paint is almost organic compound, except for dispersion medium water, pigments and fillers; Due to different varieties, organic compounds account for 8% to 35% of the paint quality. This shows that the architectural coating industry is a big industry involved in organic matters.
The role of paint in all walks of life in the national economy is enormous and its contribution is indispensable, but its disadvantages are also obvious and cannot be ignored.
About 75% of the raw materials used to manufacture coatings are from petrochemical industry, and some are from natural oils and resins, which is a huge number. The earth's ecological resources, such as natural oils and resins, are extremely limited, and the use of these resources has led to a phenomenon of competition with the people. There are 5 billion people in the world, but many people are hungry and malnourished. The vast majority of paint resources come from underground oil and coal, which are not "inexhaustible". Scientific research has proved that, from the perspective of element abundance in the earth crust, hydrogen is only 0.1% (mass Clarke number), and carbon is only 0.35% (mass Clarke number). Organic compounds are basically composed of carbon and hydrogen, which shows how little the organic storage on the earth is, and it can not be used up. In the past hundred years, especially in the past decade, wars of fighting for and plundering resources under various names have occurred repeatedly.
Inorganic silicate mineral coatings have been used for a long time. It has been more than one hundred and thirty years since Adolf Kemm, a German chemical, obtained a patent for potassium silicate mineral coatings in 1878. The adhesive of the coatings is potassium silicate glass (i.e. potassium silicate aqueous solution). Its coating film is still in existence since 1890. It has never been re coated in the middle and is still intact, bright and beautiful. This shows that potassium silicate mineral material can stand the test of changes in environment, atmosphere, natural climate, time and other factors, and its performance is excellent. At the same time, it also shows that the coating effect of a good coating is inseparable from the correct coating matching and strict and skilled construction technology (therefore, some people must correct the misconception that the use of architectural coatings is like a "point and shoot camera", and the construction has no technical content, and good results can be obtained by painting at will).
The original Kem potassium silicate mineral coating is two-component, which is prepared carefully and has strict construction requirements. In order to make potassium silicate mineral easy to use and more excellent in performance, chemists from Germany and Kem Paint Company have improved the two-component formula, which is the "one component silicate emulsion paint" that appeared in the 1970s. They optimized the proportion of silicate and modified resin to make the mineral coating nonflammable or incombustible, and improve other properties of the coating.
Japanese chemists have done a lot of fruitful work on the research of silicate mineral coatings and obtained many patents. However, although there are many patents on the research of sodium silicate as adhesive, its modification, production and construction are very strict and complex, so it is unknown where it is used and the effect is unknown. Some people in China have used sodium silicate as the adhesive to make architectural coatings (not the kind using polyvinyl alcohol), but the effect is not ideal. Other silicate adhesives (such as lithium silicate) have less resources and are too expensive, which wastes resources when used for building coatings. The best choice is to use potassium silicate or silica sol as the binder of inorganic mineral coatings.
Good economy and nearly unlimited resources. According to the data, the abundance of oxygen in the earth crust is 49.13% (mass Clarke number) and the abundance of silicon is 26.0% (mass Clarke number), which are the first two elements in nature. The earth crust where we live is almost composed of silicate and silicon dioxide, and its storage capacity can be described by Clark number. (Clark is an American chemist. The Clark number is the element abundance represented by the atomic number, which is far greater than the astronomical number.) The abundance of potassium is 2.35% (mass Clark number), which is the source of potassium silicate adhesive. Inorganic silicate mineral coating is water-based, with water as the dispersion medium, and its components are non-toxic, tasteless and free of environmental pollution. The coating has excellent permeability (0.5-2.0m): it combines with the silicate base to form a siloxane bond, which is integrated into a whole with the same performance. Unlike architectural paint and latex paint, it is just a layer of skin film. The combination with the base layer is only physical adhesion (intermolecular force) and partial hydrogen bonding (bond energy is only 8-10KJ/mol).
