Coating processes – Immersion or partial immersion – Running lengths
Reexamination Certificate
1998-07-14
2001-08-07
Bareford, Katherine A. (Department: 1762)
Coating processes
Immersion or partial immersion
Running lengths
C427S434600, C118S405000, C118S420000, C156S441000, C156S296000
Reexamination Certificate
active
06270851
ABSTRACT:
TECHNICAL FIELD
1. Field of the Invention
The present invention relates to an apparatus and an economical process for continuously coating fiber filaments by passing the fiber filaments through a molten resin closed die. More particularly, the present invention relates to an apparatus and an economical process for continuously coating the fiber filaments wherein each filament of a fiber bundle is coated continuously in a narrow flow path of a zigzag shaped tunnel formed between an inner die member and an outer die member along the fiber filaments moving direction.
2. Description of Prior Art
For the coating of a fiber bundle, the resin should be impregnated enough into a bed layer of the fiber bundle which is composed of quite a lot of fiber filaments while the fiber bundle stays in the resin of the die so that the fiber filaments may be drenched as much as possible.
According to the theory, in order to satisfactorily obtain a well impregnated resin coated fiber bundle, it is required to increase the penetrating time T, the space or pores between the fiber filaments S, the pressure P and the contact area Ac between the molten resin and the external layer of the fiber bundle for impregnating the resin into the fiber bundle, while the viscosity of the resin V and the depth Dp of the fiber bundle for penetrating the resin into the fiber bundle are decreasing.
Based on such principle, processes for coating fibers which have been used widely up to now can be classified into the following two categories, one being a process which employs cylindrical pins or lobes along with fiber tension to spread apart monofilaments and promote resin impregnation of the fiber bundle in a molten resin die. The process aims for the improvement of impregnation of fibers by the effect of the penetrating time T, the pressure P mainly and the contact area Ac partially.
Another process enhances the impregnation of the fibers by alternating convex and concave pins in a molten resin bath or a die whereby the effect of reducing the depth Dp of the fiber bundle is added to the first process by introducing the concept for spreading the fibers.
As a method for producing fiber composite material by using the first process, U.S. Pat. Nos. 3,993,726, 4,439,387, 4,549,920 are disclosed.
As another method by using the second process, U.S. Pat. Nos. 4,728,387, 4,864,964, 4,939,002 are disclosed. This process showed the fibers on a convex pin could be spread widely.
As another method by using the second process, U.S. Pat. Nos. 5,133,282, 5,236,743 showed a concave pin which can make a single point to group the fibers, and a convex pin and their combination designed by an approximate equation. The convex pin which has a distribution of radius centered by a horizontal axis is symmetrical relative to a central maximum radius. The convex and the concave pins make it possible to spread very widely the fibers on the convex pin provided that all the individual lengths of filaments in a fiber bundle are same between an concave pin and another concave pin.
Actually it is very difficult to be same the filaments lengths from die inlet to die outlet because the approximate equation is literally approximated comprising assumptions, and there are quite a few parameters in association with the shapes of the pins and their alignment. It is very difficult to consider all the design parameters and to avoid the extreme breakage of filaments due to different velocity between adjacent fibers at high production rate. Thus, not only mechanical property of the end product is lowered dramatically but also the increasing of the yield velocity would meet many limitations. Moreover, in producing many fiber-reinforcement strands, when the above-shaped pins are used, the volume of the die or resin bath has to be increased so inefficiently that the resin-residence time in the die or resin bath is increased and the risk of resin decomposition is arisen.
SUMMARY OF THE INVENTION
The present invention is intended to overcome the above difficulties of the conventional processes.
An objective of the present invention is to provide an apparatus for preparing a resin coated fiber composite of a rod shape, tubular-shape or plate shape, comprising a plurality of first members having an annular shape with a semi-circular ring shaped internal surface, a plurality of second members having a disc shape with a semi-circular ring shaped external surface, a plurality of first connectors for assembling the first members, a plurality of second connectors for assembling the second members, an outer die member semi-assembled with the plurality of the first members and the first connectors, an inner die member semi-assembled with the plurality of the second members and the second connectors, a heater disposed outside of the outer die member, the heater being a primary heat source for heating molten resin, an inlet nozzle for inlaying fiber filament bundles, an outlet nozzle for outlying fiber filament bundles, a zigzag shaped tunnel formed between the inner die member and the outer die member for providing a flow path of the fiber filaments, and a plurality of resin inlet ports disposed at a center surface section of the outer die member to fill molten resin in the zigzag shaped tunnel, and pressurize the flow path of the fiber filaments.
Another objective of the present invention is to provide the zigzag shaped tunnel for continuously contacting the fiber filaments with the pressurized molten resin in the flow path, the fiber filaments are dispersing and forwarding to an imaginary angle point of a cone shape along with the semi-circular ring shaped internal surface of the first member and the semicircular ring shaped external surface of the second member alternately, the cross sectional areas of the zigzag shaped tunnel varies through the flow path, and the fiber filaments are maintained constant length and tension all along the flow path.
Another objective of the present invention is to provide the semi-circular ring shaped internal surface of the first member and the semi-circular ring shaped external surface of the second member are either one type of embossed, uneven or even type.
Another objective of the present invention is to provide the semi-assembled outer die member and the semi-assembled inner die member are fixed to the inlet nozzle and the outlet nozzle through a plurality of axis.
Another further objective of the present invention is to provide a process for preparing a resin coated fiber composite of a rod-shape, tubular-shape or plate-shape, a plurality of fiber filaments being continuously coated in a manner of alternating sequence through a narrow flow path of a zigzag shaped tunnel formed between an inner die member and an outer die member, the process comprising steps of: spreading the plurality of fiber filaments by passing through a first member having a convex-concave portion of a semicircular ring shaped internal surface to prevent fracture of the fiber filaments, and sequentially by tensioning through a series of a second member having a semi-circular ring shaped external surface and the first member having the semi-circular ring shaped internal surface all along the narrow flow path of the zigzag shaped tunnel to maximize molten resin penetrating surface area; impregnating pressurized molten resin into a plurality of widely spreaded fiber filaments continuously by passing through the series of the first and second members all along the narrow flow path of the zigzag shaped tunnel to maximize molten resin penetrating time, wherein the pressurized molten resin is filled in the narrow flow path of the zigzag shaped tunnel, supplied from a plurality of resin inlet ports disposed at a center surface section of the outer die member, and exerted toward both ends of nozzles, and wherein pressurization of the molten resin maximizes penetrating the molten resin into pores of the fiber filaments and minimized possibility of resin degradation; stranding a plurality of resin-coated fiber filaments continuously by passing through a final set of the first
Baek Deog-Man
Lee Jae-Shik
Park Soon-Ho
Park Soun-Hie
Bareford Katherine A.
Daelim Industrial Co., Ltd.
Fulbright & Jaworski L.L.P.
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