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The three-wheeled cabin scooter has been developed as a utility vehicle, which the rider can operate without getting wet when it rains lightly. A large plastic windshield installed a wiper was used for the first time. Scratching of the windshield surface by the wiper blade has become a new concern in addition to transparency, impact resistance and weatherability. The authors solved the concern about windshied scratching by applying a silicone hard coat on the polycarbonate resin surfaces.

In the consideration of safety to health, many countries have recently been enforsing regulations on the use of asbestos. To keep abreast of this trend, it has become necessary to replace the gasket materials currently used in the cases and the covers of motorcycle engines with non-asbestos materials. The gaskets used in motorcycles are subjected to extremely severe sealing loads and temperature in the small and high performance engines. They are required to have excellent sealability and creep relaxation characteristics at high temperature. Under such conditions, it is extremely difficult to substitute non-asbestos materials for asbestos which has superb material characteristics such as higher heat resistance and greater aspect ratio (length of fiber/dia.).

Polypropylene (hereinafter PP), as compared with other plastic materials, has lower specific gravity of 0.91, offers higher impact resistance and easier molding, and is less expensive. For these reasons it is now in wide use in the manufacture of various automobile parts. When PP is for exterior use, such as for automobile bumpers or motorcycles fenders, it is rather a common practice to apply paint for cosmetic purpose. However, due to its high crystallinity and low polarity, PP has some problems, particularly as to its ability to retain paint on its surface. The purpose of this study is to improve its ability to retain paint on its surface. To achieve this, the study was concentrated on its surface pretreatment as well as on the improvement of PP itself. Further it was seeked to develop a paint which is highly durable and which, at the same time, is flexible enough to be applied to PP automobile exterior parts.

This paper compares the material usage percentages of the Honda Civic CRX, on which a large number of newly developed plastic parts are used, to other representative Japanese car models and describes the characteristics of the newly developed materials and their technological applications. Specifically, the development and application of thermoplastic resins for outer body panels, is discussed, with clarification of their use in the body structure, mathematical analysis of their dimensional changes due to thermal expansion, and a discussion of their characteristics by comparing the components and properties with existing plastic materials including a detailed description of their impact resistance properties as injection molded parts.