CH640572A5 - Composite fiber and shaped article of fiber called. - Google Patents

Description

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1. Composite fiber characterized in that it comprises a resin, several glass fibers and at least one carbon fiber.

2. Composite fiber according to claim 1, characterized in that the said resin consists of a thermosetting polyester.

3. Composite fiber according to claim 1, characterized in that, as regards glass and carbon fibers, they are distributed between 35 and 98% of the weight with regard to glass, and between 65 and 2% weight when it comes to carbon.

4. Composite fiber according to claim 3, characterized in that the amount of said resin varies between 20 and 45% of the weight of said composite fiber.

5. Composite fiber according to claim 1, characterized in that said resin is chosen from the group formed by polyethylene, polypropylene, polyamides, polyurethanes, polyesters, epoxides and mixtures thereof.

6. Composite fiber according to claim 1, characterized in that said fiber is impregnated with a resin consisting of thickened and uncured polyester.

7. The composite fiber according to claim 1, impregnated with a resin cured in stage B.

8. Fiber according to claim 1, wound on a reel.

9. Fiber according to claim 1, characterized in that the respective volumes of the carbon and glass fibers which constitute the composite fiber vary between 50 and 5% as regards carbon, and between 5 and 50% as regards concerns glass.

10. Article formed of the composite fiber according to claim 1, helically wound and compressed.

11. Article according to claim 10, characterized in that said composite fiber is wound at an opening angle of approximately 85.4 ".

12. Article according to claim 10, characterized by the presence of three layers of fibers wound helically.

13. Article according to claim 10, characterized in that said resin consists of a thermosetting polyester.

14. Composite article according to claim 10, characterized in that, as regards the glass and carbon fibers composing said composite fiber, they are distributed between 35 and 98% of the weight with regard to glass, and between 65 and 2% of the weight with regard to carbon.

15. Composite article according to claim 10, characterized in that said fibers are impregnated with a resin consisting of thickened and uncured polyester.

16. A composite article according to claim 10, impregnated with a cured resin in stage B.

17. Article according to claim 10, characterized in that the fiber is wound on spools.

18. Article according to claim 10, characterized in that the volumes of the glass and carbon fibers which constitute said article vary respectively between 50 and 5% as regards carbon and between 5 and 50% as regards glass.

19. Article according to claim 14, characterized in that the amount of said resin varies between 20 and 45% of the weight of said article.

20. Article according to claim 10, characterized in that said resin is chosen from the group formed by polyethylene, polypropylene, polyamides, polyurethanes, polyesters, epoxides and mixtures thereof.

Recently, the demand for plastic structures has grown rapidly. Unidirectionally reinforced resin sheets have been transformed into structural parts for automobiles such as, for example, transmission supports, door beams and the like.

These reinforced sheets contain glass fibers which have been wound helically on a mandrel according to a crossed design and whose glass weight varies between 60 and 80%. While the reinforced sheets which contain a large proportion of glass produce parts with excellent resistance, it is often desired to obtain better modulus characteristics than is usually achieved.

The carbon fibers contained in the molded parts provide good modulus characteristics to them. Mixtures of carbon and glass fibers have therefore been used in resins, so as to benefit from the respective qualities of resistance and modulus that these provide to the resin matrix. Numerous difficulties have been encountered in attempts to wind glass and carbon fibers to make reinforced sheets. Frequently carbon fibers break in the resin bath or on the die. It seems that this is due to viscosity tensions which are exerted on the wire during its passage in the bath and which cause the fraying of the wire and finally its rupture.

We have now developed a composite fiber comprising at least one carbon fiber with resin and glass fibers. This new composite fiber can be used for the manufacture of resin sheets reinforced at the same time with glass and carbon fibers.

According to the process revealed by this description, new glass and carbon fibers are wound on a mandrel to manufacture resin sheets. In the process for the preparation of these sheets, glass fibers from a reserve are passed through a bath, where they are completely wetted. The glass fibers are then passed through a die which adjusts the amount of resin to be included in the glass fibers. The carbon fiber which is used to make the composite material is introduced directly to the back of the die used to adjust the resin content of the glass fiber and it is brought into contact with the resin at the point where the latter flows back from the die. . By introducing carbon fiber at this point, the fraying of the fiber is eliminated, the fiber is well wetted and this allows it to be easily wound on the mandrel without risk of breakage as is the case during passage through the resin bath. The composite fiber thus obtained consists of resin, a multitude of glass fibers and at least one carbon fiber.

When preparing resin sheets reinforced with glass + carbon which have good structural characteristics and which contain between 55 and 80% 4-carbon glass and 45 to 20% resin by weight, first cover the glass and carbon fibers with a resin and then wrapped on a mandrel. In the following description of the process, given by way of example, reference is made to the appended drawings:

fig. 1 is a perspective board of the equipment used to manufacture the resin + glass + carbon sheets according to this invention;

fig. 2 is an enlarged perspective view of the part relating to the application of the resin during the process described in FIG. 1, and fig. 3 is a view looking into the resin application tank 9 which shows the die 13 and the entry point of the carbon fiber.

In the preparation of the resin + glass + carbon composite material, a multitude of glass fibers is used. As shown in fig. 1 by way of illustration, six rolls of glass fibers are used only 2. These rollers 2 are mounted on a support or reel holder, not shown, and the glass fibers 1 coming from the rolls are wound in a thread through the openings 4 and 5 located in the wall 3 which is usually a metal plate. In fig. 1, glass rollers of the upper row have the end of their wire passed through the opening 5, and those of the lower row have the end of their wire 1 passed through the opening 4. The combined wires physically form two ribbons of glass which pass under the guide bars 11 and 15 in the resin tank 9. These wires 1 and 1 ′ are led through the dies 12 and 13 located at

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the front end of the tank 9. Two rollers 18 and 18 'containing the carbon fibers 8 and 8' are mounted at the top of the wall 3. The carbon fibers 8 and 8 'are introduced into the die holes 12 and 13 respectively by passing through the reflux of resin 14 which accumulates when the die removes the excess resin from the surface of the glass strands 1 and 1 ′. The consolidated glass + carbon fibers 19 and 19 ′ which exit from the die holes 12 and 13 form a reinforced strip 17 by passing through the opening 22 located on a movable guide 21, and this ribbon is wound on a rotating mandrel 15 until 'to obtain the desired thickness. When the composite material has reached the desired thickness, the mandrel 15 is stopped, the resulting sheet is cut and the process is repeated.

The process generally described in the drawing is subject to numerous modifications. For example, if we show a single ribbon 17 which is wound on the mandrel 15, it is only for purposes of illustration. Several ribbons can be wound simultaneously on the mandrel which come from an opening row. Similarly, the number of strands used to make the fiberglass 1 'can be varied. One can therefore use a single strand or more strands to form the fiber 1 '. Usually one uses between 1 and 10 strands or even more to compose the fiber 1 '. The width of the ribbon 17 forming the final product decides the number and diameter of the fibers that will be used to form the ribbon. By width is meant the thickness measured perpendicular to the direction of the tape.

In the method presented in the drawing, the mandrel 15 rotates on an axis clockwise by means of a suitable motor. The guide 21 moves back and forth in the horizontal plane and deposits the composite tape 17 on the mandrel 15.

The ribbon 17 is deposited on the mandrel 15 at a predetermined opening angle so as to provide directional reinforcing properties to the finished material. The opening angle is the acute angle formed by the intersection of the ribbon 17 on the body of the mandrel, with a line located on the mandrel which is parallel to the longitudinal axis of the mandrel. In the structural sheets produced by this process the angle is between 60 and 89 °. The angle of winding of the ribbon 17 on the mandrel is the angle formed by the intersection of the ribbon 17 on the mandrel with a line located on the mandrel and which is perpendicular to the longitudinal axis of the mandrel. Normally in this process, this angle is between 1 and 30 °. During the normal course of operations, the mandrel 15 rotates continuously and the guide 21 makes a back and forth movement in the horizontal plane which makes it possible to deposit the ribbon 17 on the mandrel 15 in a cross pattern to form layers of composite material on the surface of the mandrel. In this publication, it is understood that a layer is formed when the ribbon 17 has covered the mandrel in both directions. The finished sheet containing the glass and carbon fibers will contain the number of layers intended to form a product having the desired density. Resin 10 is constantly added to the tank 9 so that there is always enough resin to completely wet the glass fibers 1 and pass it under the bars 11 and 15. This can be realized by an automatic feeding device or manually. The tray 9, along the width of the mandrel 15, can remain stationary or it can be made to move back and forth in the horizontal plane which is coordinated with the movement of the plate 21. The fiber and articles made according to this invention can be fashioned from any suitable resin. Suitable thermoplastic resins include polyethylene, polypropylene and polystyrenes. Thermosetting resins used in the system usually include vinyl esters, fast setting epoxy resins and multi-purpose polyester resins. Isophthalic / polyester resins have been found to be particularly effective in making the composite materials of this invention and will be chosen first.

One can choose epoxy resins hardening in stage B and thickened polyesters because they can be stored after the separation of the mandrel, then they are cut and molded at a later date. Typical polyesters which can be used in this invention belong to the classes of resins which are presented in US Patent No. 3840618. An important parameter in the preparation of composite materials is the regulation of the amount of resin in the finished product. In this process, this is achieved by adjusting the dimension of the die holes 12 and 13. It has been observed that in general these orifices must have a diameter of between 0.36 and 2 mm.

The carbon fibers introduced into the system can be drawn directly from the wall 3 or from a spool holder located near the tank 9. The entry point of the carbon fiber into the resin tank is an important parameter which intervenes in the success of forming the composite ribbons 19 and 19 '. The residence time and the tension on the carbon fiber must be minimized in order to prevent damage or degradation of the fiber. So it is important that the fiber is introduced into the system at or near the entrance to the die and, preferably, at the central location where the resin overflows from the die. This prevents excessive tension on the fiber as it passes through the resin and allows the fiber to enter the system without undergoing excessive viscous tension.

The composite sheets obtained by this process generally contain between 50 and 5% of carbon fiber and between 5 and 50% of glass fiber, this measured in volumes. However, in this invention is included a range of about 20 to 95% glass and about 80 to 5% carbon fiber, this measured by volume. This corresponds to between 35 and 98% of the weight with regard to the glass and with between 65 and 2% of the weight with regard to the carbon. The glass and carbon fibers are introduced into the system and the composite fiber is wound on the mandrel at speeds between 15 and 150 m / min.

Resin is poured over the composite fibers and usually the sheets formed are placed between two layers of clear plastic such as polyethylene. So, in practice, the mandrel is first covered with a layer of polyethylene before we start to wind the composite fiber. When a determined number of layers has been reached, the mandrel is stopped and the composite fiber sheet is covered with another layer of polyethylene, then the whole of the mandrel is separated. By sandwiching the sheet of composite material between two sheets of polyethylene, one can easily handle the composite sheet and can store it until it is needed. By applying heat to the composite sheet during molding, a hard, solidified part is obtained.

Carbon fibers are obtained by treating organic fibers by pyrolysis. So carbon fibers were obtained by pyrolysis of rayon precursor yarn, polyacrylonitriles and the like. Several types of these threads are commercially available today and are described in the literature (“Modem Plastics Encyclopedia”, 54.10A, p. 172, October 1977; “Advanced Materials”, CZ Carroll-Porczynski, Chemical Publishing Co., NY 1962; “Industriai Chemistry”, 7th Ed. P. 342, Van Nostrand Reinhold Co., NY 1974).

A fiber particularly useful in this invention is a fiber called Celion ", manufactured by Celanese Corporation. In a typical application of the process described here, a sheet of resin + glass + carbon was made by filling the resin tank with a mixture of 90 parts of a polyester isophthalic resin, 10 parts of monomeric styrene, 0.5 part of zinc stearate, 1 part of tertiary butylperbenzoate and 3.5 parts of magnesium oxide as thickening agent. glass fibers were mounted on a rack, each reel containing type K-37 glass fibers.

These fibers are composed of 400 glass filaments, each filament having a diameter of 0.00127 cm. Three glass ribbons are then formed from four coils and they are brought together before passing through the resin tank. A total of three ribbons pass through the resin tank at a speed of 30-60 m / min. Resin, the composition of which is described above, is continuously supplied to the tank during the passage.

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The three glass threads which pass through the resin tank are drawn through three precision dies, each having a diameter of 0.11 cm. Three carbon fibers are introduced into the system by passing them separately through each die into which the glass fibers have been introduced, this on the side of the resin tank, so that each carbon fiber entering the die is covered by the excess resin which overflows from the die due to the passage of fiberglass. By passing through the die, the carbon fiber wets with the resin contained in the die and physically combines with the glass ribbon passing through the die so as to form three glass ribbons + consolidated carbon. These three consolidated ribbons pass through three eyecups located on a movable guide placed above the mandrel. The fibers are wound side by side on the mandrel at an opening angle of 85.4 ° and a winding angle of 4.6 °. The movable guide passes back and forth over the mandrel and the fibers are wound up until three layers are formed on the mandrel. The mandrel is then stopped and the composite sheet is removed. The finished sheets are cut to any size so as to form panels later. These panels are then transformed into structural parts.

While this invention has been described by winding the fibers on a mandrel, it is also possible to use these composite fibers of resin, glass and carbon in other ways. The fiber would be wound on a spool for later use. The reels could be unwound for use in another location. The coils could also be used in the weaving of reinforced plies or else in the reinforcement of certain particular parts. We could also braid the fibers into cables. On the other hand, the fibers could be brought directly from the bath onto a belt in the form of loops and then passed to the rolling mill.

While this invention has been described in accordance with certain conditions, it is not limited thereto except by what is given in the accompanying claims.

1 sheet of drawings