Thermal spray compositions come in powder form and can be applied to a surface by thermal spraying. The term “thermal spraying” refers to process in which a coating material feedstock, (e.g., thermal spray composition), is heated and propelled as individual droplets or particles onto the surface of a substrate. The coating material is heated by the applicator (e.g., a thermal spray gun) by using combustible gas, plasma flame or electric hot air to heat and melt the plastic particles into droplets, which are propelled out of the spray gun by compressed gas. When the coating material particles strike the substrate to be coated they flatten, flow and melt into adjacent particles to form a continuous film. It is this film that coats the surface.
Different types of thermal spray compositions are available on the market today which can be used to coat various surfaces such as metal, paper, wood, plastic, concrete and the like. These thermal spray compositions include compositions comprising thermoplastic powders. Although thermoplastic powders can be thermal sprayed into a coating, each thermoplastic powder presents special problems once applied, making these coatings limited and unreliable. For example, some thermoplastics when sprayed produce coatings that peel, crack, and pull back at the edges or even clump upon application. Therefore, what is needed in the market today are thermoplastic compositions that can be thermal sprayed using specialized equipment and once applied produce a coating that adheres to the surface, does not crack, peel or exhibit edge pull back and edge lifting.
After considerable experimental testing, it has been determined that inherent problems associated with thermal sprayed thermoplastic coatings are resolved by adding another type/species of thermoplastics. In other words, thermal spraying a composition combining at least two specific but different types and/or species of thermoplastics produce coatings free of the problems discussed above that are associated with coatings resulting from thermally spraying thermoplastics individually. The compositions of the present invention comprising at least two thermoplastics have the aforementioned characteristics as well as others and overcome the shortcomings of the prior art discussed above. The present invention is further described in the sections below.
USPTO Backgrounds
USPTO Backgrounds