Application of silane-based polymer to surface coating. The merits are described fundamentally.

What is it about?

Silane resin coatings, their structure, characteristics, and applications are reviewed. Generally, silane compounds are classified into two types, silicone and silicates, and make up organic paints and coating agents that are easy to handle and inexpensive and have high designing capability. However, they are vulnerable to ultraviolet light and heat due to the carbon–carbon bonds which also accounts for their lack of durability. Therefore, the authors herein have developed and investi- gated the applicability of alkoxysilane compounds for coatings and painting films. Conventionally, the mechanical strength and adhesion force to the substrate have not been good for silane polymer resins. However, the newly investigated and devel- oped alkoxysilane compound films could solve these conventional problems. The concepts of the novel silane compound films and the rational for the research and development will be described. Further, the application possibilities in many indus- trial fields will be introduced in this chapter, with concrete examples mentioned. Keywords

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Why is it important?

As representative organic polymers for coating, paints, and binders, the following examples can be mentioned: alkyd resin, urethane resin, acrylate resin, epoxy resin, and polyester resin. These organic polymers have a basic structure composed of car- bon–carbon bonds and various unique characteristics can be expressed depending on the combined species when monomers bind to form polymers. Basically, organic polymers for painting and coating have characteristics that they could improve work- ability by dilution or addition of chemicals as additives and also extend the applica- tion. Due to their high flexibility, these paint films could follow the deformation of substrate (i.e., shrinkage) as well as high resistance against cracking and spalling. Even though paints and coatings composed of organic polymers might seem to be good in all aspects, they inevitably have some weak points. To name a few, there are phenomena that affect their applicability that occur on a daily basis. When a person lounges against a wall, their clothing may be contaminated with a white powder. This is called chalking where the main backbone of organic compounds is composed of carbon–carbon bonds that are collapsed by ultraviolet light, causing the paint film to be deteriorated and resulting in shabby-looking surfaces. Also, since the paint films could be composed of nearly all organic compounds, they do not have high heat resistance, potentially causing a fire to spread. This could be controlled by the addi- tion of a fire-retarding material. However, decomposition at approximately 200°C could form toxic gas or cause the painted substrate materials heavy damage. When steel is used as substrate, rust might form at the site of spalling, since it would be exposed to a high-temperature atmosphere directly. Therefore, heat resistance is often required for applications.Silane polymers are often used to compensate for such a weak point in the applica- tion. It has a main backbone composed of Si–O–Si. This is called a siloxane bond, and the technical term corresponds to an all-inclusive expression for organo- polysiloxane possessing various organic groups as a side chain. In the broad sense, quite a few compounds synthesized in various ways belong to the category at present. The common characteristics for compounds in this category are high heat resistance, cold hardness, insulating, repellency, and a weathering, all of these properties deriving from the siloxane bond itself. These merits have led the compounds to be used inversatile applications such as lubrication, caulking materials (filling chinks in walls), cooking devices, etc. In the painting and coating fields, silicone and silicate are typically used. However, these materials are difficult to use from both stability and handling perspective. Therefore, the frequency of their use has not been very high at this point. In this chapter, the technology for the production of silane polymers as painting materials, their characteristics, and their applications will all be described.

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