In order to protect the products from damage due to mechanical, physical and chemical influences from the outside, various coating layers or coating films are being applied to the surface of electric and electronic devices such as mobile phones or various display devices, etc., components of electronic materials, household appliances, automobile interior and exterior materials, or various molded products such as various plastic products. However, scratches on the coated surface of the products or cracks due to external shocks deteriorate the appearance characteristic, main performance and lifespan of the products, and therefore various studies are being conducted to protect the surface of the products, thereby maintaining the quality of the products for a long period of time.
In particular, research and interest in coating materials having self-healing properties have been rapidly increasing in recent years. The self-healing property refers to a property in which, when scratches are made on the coating layer by an external physical force or stimulus applied to the coating layer, the damage such as scratches is gradually healed or reduced itself. Although various coating materials exhibiting such a self-healing property, or mechanisms of the self-healing property are known, in general, a method for using a coating material exhibiting elasticity is widely known. That is, when such a coating material is used, even if a physical damage such as scratches is applied on the coating layer, the damage site is gradually filled in because of the elasticity of the coating material itself, and thus, the self-healing property described above may be exhibited.
However, in the case of a conventional coating layer exhibiting the self-healing property, it had disadvantages in that the mechanical properties of the coating layer such as hardness, abrasion resistance or coating strength, etc. were insufficient as elastic materials were mainly included. In particular, in the case of applying a coating layer exhibiting a self-healing property to the exterior of various household appliances such as refrigerators or washing machines, etc., the mechanical properties of the coating layer are required on a high level, but in most cases, the coating layer having a conventional self-healing property could not satisfy such high mechanical properties. Accordingly, when a strong external stimulus was applied to the existing coating layer, there were many cases where the coating layer itself was permanently damaged, and the self-healing property was also lost.
Due to such problems of the prior arts, there has been a continuing demand for the development of a technique that enables the provision of a coating layer or film that exhibits further improved mechanical properties together with excellent self-healing properties.