Olefinic resins, as well known in the art, have excellent moldability and good heat, solvent and chemical resistance; and, consequently, they enjoy a wide range of industrial applications, e.g., for the manufacture of automobile components. However, since they are chemically inactive owing to their non-polarity and have low solubility due to their high crystallinity, it is difficult to paint articles formed therefrom.
For instance, an automobile bumper made of an olefinic polymer or composition is normally coated with a polyurethane paint. However, in order to carry out the painting process, the molded articles should first undergo various surface treatments such as electric treatment, e.g., corona discharge treatment, plasma treatment and ultraviolet or electronic irradiation treatment, mechanical treatment, flame treatment and oxygen or ozone treatment before coating with a polyurethane paint. Needless to say, the above surface treatments are costly and time consuming.
Accordingly, in practice, the molded article, e.g., bumper, is coated with a primer and then applied with a polyurethane paint thereto. Since this method also requires extra cost and production time, search for a satisfactory solution has continued.
In an attempt to solve the problem, there have been suggested a process which comprises adding a rubber material and/or an inorganic filler and an ethylene copolymer containing a polar group to an olefinic resin(see PCT International Publication No. WO 88/07 564); and, similarly, another process which comprises grafting an olefinic resin or a molded article thereof with a compound having a polar group in the presence of a peroxide(see JP 01 236 214 and EP 312,664). The former does not entail a significant improvement in its paintability, whereas the latter is not appropriate for a continuous production process due to various process requirements associated with the drying procedure and the dispersion and grafting of monomers. Accordingly, needs have continued to exist for the development of a polyolefinic composition which may be painted with a commercially available paint in a conventional coating process which is normally conducted at a temperature of 80.degree. to 120.degree. C.
USPTO Backgrounds
USPTO Backgrounds