Plastic and nonmetallic article shaping or treating: processes – With printing or coating of workpiece – Coating or impregnating workpiece before molding or shaping...
Reexamination Certificate
1999-03-16
2001-11-20
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With printing or coating of workpiece
Coating or impregnating workpiece before molding or shaping...
C264S137000, C264S211140, C264S257000, C156S180000, C156S181000, C427S434700
Reexamination Certificate
active
06319443
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing fiber reinforced plastics (“FRP ”) by means of a drawing method which is especially suited for a polymer insulator.
2. Description of Related Art
FRP, in which glass roving aligned in one direction to which thermosetting resins are immersed and the resins are cured, is light in weight and has a high strength. Therefore, it is preferably used as a core member of a polymer insulator for a power-transmission line or the like. There is known in the art a well known manufacturing method for drawing such an FRP having the steps of: aligning a fiber itself or a plurality of fibers for reinforcing such as roving, yarn, mat, cloth or the like, immersing liquid resins into the fiber or the fibers by passing it or them in a resin supply zone, and curing the resins by means of thermosetting reaction by passing it, in a die to obtain a forming product having a continuous and same cross section.
In the known drawing method mentioned above, bubble inclusions are liable to be generated in the resins during passing of the fibers through the resin supply zone. In addition bubble inclusions also occur because the plurality of fibers is aligned in one direction to which resins are immersed and are drawn in such a manner that the fibers shrink at an inlet of the die. Therefore, there is the drawback that a forming product including bubbles is hardened as is. In order to eliminate the bubble inclusion problem, there is known a method of degassing by means of a vapor degassing step arranged prior to the drawing step using the die (JP-A-4-305439) and a method of removing bubbles by using a plurality of divided paths for passing forming materials arranged at an inlet side of the die (JP-A-7-117141).
The known methods mentioned above show a sufficient corrosion resistivity and mechanical properties required for a general construction member. However, when the inventors used the thus obtained FRP as the core member of the polymer insulator for a high voltage electric insulation member, it was discovered that the an electric insulation breakage property of the FRP was not sufficient. After examining the FRP in detail, it was found that a plurality of invisible slender micro-gaps were generated in the FRP and those micro-gaps affect the electric insulation breakage property. Moreover, if the slender micro-gaps remain in and between single fibers, the fibers, including air, are supplied into the die. In this case, it was found that the electric insulation property is affected since such air is extended in or between the fibers when the fibers shrink at the inlet of the die.
SUMMARY OF THE INVENTION
It is a primary object of the invention is to eliminate the drawbacks mentioned above and to provide a method of manufacturing fiber reinforced plastics which can provide the FRP's preferred for high voltage electric insulation members such as an insulator or the like.
According to the invention, a method of manufacturing fiber reinforced plastics by means of a drawing method having the steps of immersing resins into fibers for reinforcing aligned in one direction, which are supplied continuously, and curing the resins immersed in the fibers by drawing the fibers into a die, comprises a step of: moving the fibers in a resin supply zone at a substantially same speed as that of resin immersing in the fibers along a direction in which the fibers are aligned.
In the present invention, the fibers for reinforcing, which are a gathering of members of plural single fiber, are moved in the resin supply zone at a substantially same speed as that of resin immersion in the fibers along the direction in which the fibers are aligned. Therefore, it is possible to manufacture the FRP with no bubbles in the fibers for reinforcing. As a result, it is possible to obtain the FRP preferred as the high voltage electric insulation member such as insulator or the like. In the present invention, the term “immersing speed” means generally a moving speed based on a capillary motion of resins in and between single fibers for reinforcing. When the fibers for reinforcing are compressed by a roller during the resin immersing step or when a plurality of fibers for reinforcing, are immersed in resin the term “immersing speed” means total speed of the above moving speed based on the capillary motion and the resin moving speed due to the mechanical compression of the fibers for reinforcing.
REFERENCES:
patent: 3855031 (1974-12-01), McNeely et al.
patent: 4481056 (1984-11-01), Kuhl
patent: 5104698 (1992-04-01), Hayashi et al.
patent: 5114633 (1992-05-01), Stewart
patent: 5176775 (1993-01-01), Montsinger
patent: 361211022A (1986-09-01), None
patent: 4-305439 (1992-10-01), None
patent: 7-117141 (1995-05-01), None
Burr & Brown
Lee Edmund H.
NGK Insulators Ltd.
Silbaugh Jan H.
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