GB2159845A - Improvements in and relating to fibre reinforcing tape - Google Patents

Abstract

In the manufacture of a fibre- reinforced plastics object, at least part of the fibre material is used in the form of a tape (11a) consisting of longitudinal, mutually parallel yarns (12a) and of transverse, mutually parallel yarns, the latter yarns making an oblique angle (17) with the longitudinal yarns. The tape (11a) is produced from a tape consisting of longitudinal mutually parallel warp yarns (12) and of weft yarns (13) which are at least substantially perpendicular thereto by passing this tape into the nip between driven rollers of a roll pair (14) and, upon its exit from the nip, while being held under tension in its longitudinal direction, by displacing it in a direction which makes an oblique angle (15) with the direction of the warp yarns (12) before their entry into the nip, and by winding the tape onto a winding-up device (16) with the parallel warp yarns (12a) directed at least substantially perpendicularly to the axis of rotation of the winding- up device or by drawing the tape into a tool (not shown in Fig. 1) for drawing profiles of reinforced plastics material. The material may be embedded in a mass of hardenable plastics material which is allowed to harden to provide a fibre-reinforced product. <IMAGE>

Description

SPECIFICATION Improvements in and relating to fibre reinforcing tape In the manufacture of tubes and other profiled products, particularly elongate products, of fibre reinforced plastics material (e.g. glassfibre reinforced plastics material), at least part of the fibre material is often employed in the form of tape which is wound in a specified number of layers around a mandrel or other body, on which the reinforced plastics product is built up. Alternatively, the fibre material, in tape form, is drawn into a shaping tool or die for creating the required profile in the reinforced plastics material. In order for the product to have the required strength in different directions, it is important that the fibre material is properly orientated in the product.A desired orientation may be difficult to achieve when using a tape where the longitudinal warp yarns and the transverse weft yarns of the fibre material are perpendicular to each other. In many applications, the problems could be solved by using a tape in which the longitudinal mutually parallel yarns and the transverse mutually parallel yarns make an oblique angle with each other. It would, of course, be a great advantage if such tapes with a varying size of said angle could be produced in a simple manner as part of the manufacturing process for producing the reinforced plastics product, since each particular fibre orientation required could be provided as needed so that the finished reinforced product would acquire the desired properties. The present invention relates to such a method.

What constitutes the invention is defined in the following claim 1.

In the simplest embodiment when using a winding up device, the tape, upon leaving the nip may be tensioned and displaced by the winding-up device on which it is to be wound up. It may also be made to pass through a nip in a second roll pair, the rollers of which are driven synchronously with the rollers of the first roll pair, before being wound up on the winding-up device. The latter method may be preferable if the tape is to be subjected to some treatment, for example an impregnation, before being wound up on the winding-up device. Also, when creating a reinforced shaped object in a forming die, it may be convenient to use a second pair of rolls, The fibre material preferably consists of glass fibre but may also consist of fibre of other materials such as different polymers (for example polyethylene glycol terephthalate, polyamide and polyacrylic nitrile) carbon or cellulose.The transversly extending weft yarns are preferably thicker than the longitudinal or warp ones, and the total amount of fibre material is preferably considerably greater, such as at least 10 times greater, in the weft yarns than in the warp yarns.

The plastics material is preferably a solventfree thermosetting resin, such as for example an unsaturated polyester resin, an epoxy resin or a urethane resin of such types as are known for use in the manufacture of glassfibre reinforced plastics materials. Both heatsettable resins and resins which are curable at room temperature can be used. In principle, it is also possible to use thermoplastics resins.

The plastics material can be supplied with the fibre material in different ways. Thus, the fibre material can be impregnated with the plastics after the fibre material has been applied or in conjunction with applying it on a mandrel or other body on which the eventual profiled object is to be shaped. It can also be supplied to the fibre material by preimpregnating the fibre material with the plastics before the fibre material is applied on a mandrel or a corresponding forming body. At least if the plastics material is supplied to the fibre material after the application of the fibre material, it is often advantageous to carry out the impregnation as some form of vacuum impregnation.In the event that the fibre material is used in a forming die, the plastics can be supplied to the fibre material either before the fibre material is moved into the die or during the passage of the fibre material through the die.

The invention will now be explained, in greater detail by way of example, with reference to the accompanying schematic drawing, wherein: Figure 1 shows schematically, in plan, a device by which the method of the invention can be performed, Figure 2 shows a modified device, Figure 3 shows a plastics object being manufactured with reinforcing material made according to the present invention, and Figure 4 shows schematically, another plastics object also being manufactured according to the present invention, this time in a die.

A spool 10 shown in Figure 1 contains a tape 11 woven from glass-fibre yarns. The tape 11 comprises lognitudinal mutually parallel yarns 12 and transverse yarns 13 arranged perpendicular to the yarns 12. The yarns 12 can, for example, consist of glass-fibre rovings with a thickness of a few tens of tex, with some four yarns per centimetre. The yarns 13 can consist of glassfibre rovings with a thickness in excess of 1000 tex, with roughly half the number of yarns per centimetre as the warp yarns. The warp of the tape 11 thus consists of sparse, fine yarns and the weft of relatively sparse, coarse yarns. The spool 10 is provided with a suitable brake device (not shown) to ensure tension in the tape 11 between the spool 10 and a nip formed between a roll pair 14 (of which only the upper roller 14a is shown in Figure 1).The roll pair 14 is driven in conventional manner by means of a motor (not shown).

After leaving the roll pair 14, the tape (now designated 11 a) while still being held in tension in its longitudinal direction is displaced laterally in a direction which makes an angle 15 with the direction of the longitudinal parallel yarns 12 before the entry of these yarns into the nip of the roll pair 14, and is wound up on a further spool, or some other suitable cylindrical winding-up device 16 with the par.

allel longitudinal yarns (now designated 12a) directed perpendicularly to the axis of rotation of the winding-up device 16. The windingup device 16 is provided with a conventional drive motor (not shown) and with a slipping brake (also not shown) of any suitable kind to compensate for the diametrical growth of the wound-on material on the winding-up device 16. After passage through the nip of the roll pair 14, the transverse yarns (now designated 13a) make an oblique angle 17 with the longitudinal yarns 12a. The angles 15 and 17 may, for example, be about 45 , and can have any arbitrary magnitude between 20 and 70'.

The device shown in Figure 2 comprises, in addition to that shown in Figure 1, a second roll pair 18, of which only the upper roller 18a is shown, as well as an impregnation device 19 and a drying device 20. The second roll pair 18 is driven synchronously with the first roll pair 14. In this case a tape 21 is obtained on the winding-up device 16 which is preimpregnated with the resin used in the device 19. In many cases, the second roll pair 18 can be dispensed with.

Figure 3 shows the use of a tape produced on the device shown in Figure 1 for the manufacture of a tube of glass-fibre reinforced plastics material. Glass-fibre tapes are wound in a large number of layers on a mandrel 30.

Each layer extends along the required length of the mandrel. The layers consist alternately in successive order of a tape 22 of the same kind as that designated 11 in Figure 1, that is, in which the weft yarns 23 extend perpendicularly to the warp yarns 23a, a tape 24 of the same kind as that designated Ila in Figure 1, that is, in which the weft yarns 25 make an oblique angle with the warp yarns 25a, a tape 26 of the same kind as the tape 22, that is, in which the weft yarns 27 extend perpendicularly to the warp yarns 27a and a tape 28 of the same kind as the tape 24 but wound in the opposite direction, that is, a tape in which the weft yarns 29 make an oblique angle with the warp yarns 29a. In the left-hand part of Figure 3, wound-on layers of the different tapes 24, 26 and 28 have been partially removed to make the underlying layers visible.In all the tapes, the warp yarns consist of rovings of a thickness of 34 tex and the weft yarns of rovings with a thickness of 1200 tex.

The number of yarns per centimetre is 4.0 in warp and 2.2 in weft. When the intended number of layers of tape have been applied on the mandrel 30, the glass-fibre material is impregnated with an unsaturated polyester resin containing 57 parts by weight of a reaction product of maleic acid, isophthalic acid and neopentyl glycol, whereby 1.5 mole of isophthalic acid and 2.7 mole of neopentyl glycol are used per mole of maleic acid, and further containing 43 parts by weight styrene and 1 part by weight benzoyl peroxide. The impregnation may, for example, take place by holding the mandrel with its glass-fibre material, possibly after evacuation, immersed in the resin. Alternatively, the resin may be supplied to the glass-fibre material during the winding of the tapes 22-26 on the mandrel 30.The hardening of the resin may take place at a temperature of 1 20 C over a period of some 3 hours.

As previously mentioned, each tape may be preimpregnated with resin before it is applied on a mandrel or other forming body, on which a reinforced object of plastics material is to be formed. A preimpregnation can be carried out in the following manner given as an example.

With reference to Figure 2, the tape 1 1 a is led through a bath 19 of a resin to which a solvent has been added, and thereafter through a drying device 20 in which the solvent is driven off, before the tape 21, in dry condition, is wound up onto the mandrel 16. The resin may, for example, consist of a bisphenol type epoxy resin (such as Araldit B from Ciba AG, Switzerland), which is solid at room temperature, to which dicyandiamide as curing agent has been added, 3 parts by weight of curing agent being used per 100 parts by weight epoxy resin. A solvent in the form of, for example, methyl ethyl ketone is added to the resin. The amount of solvent used is desirably selected so that the resin is given a viscosity which gives the desired amount of resin take-up on the impregnated tape.The preimpregnated tape 21 and a tape of the same kind as the tape designated 11 in Figures 1 and 2, preimpregnated in an analogous manner, can be used for manufacturing a tube. The tape is then wound, on a mandrel in the manner illustrated in Figure 3 and previously explained with reference to that Figure. The glass fibre material contains in this case all the necessary resin, so no additional supply of resin to the windings on the mandrel is required. The curing can be carried out at a temperature of 1 40 C for about 10 hours.

Figure 4 illustrates the use of the invention for the continuous production of profiled shapes of reinforced plastics. After the tape 11, in the same way as shown in Figure 1, has passed through the nip of the roll pair 14 with the rollers 1 4a and 1 4b, the tape is drawn through a tool 31 for pulling profiles of reinforced plastics material. For that purpose, the tool 31 is arranged so that the parallel longitudinal yarns 1 2a, after their passage through the nip of the roll pair 14, make an angle 15 with the parallel longitudinal yarns 12 before their passage through the nip. The longitudinal parallel yarns 1 2a are then aligned with the transport direction of the tape 1 1a into and through the tool 31. To prevent confusion, only one of the tapes has been shown in Figure 4.In reality a large number of tapes of the same kind as tape Ila would be used, each one produced from a tape 11 with its own roll pair 14. Of course, in addition to tape Ila, a tape with a different yarn orientation may be used, such as, for example, a tape of the same kind as tape 11. After passage through the roll pair 14, the tape 1 1 a and the other tapes can be fed below the liquid surface in bath 19 by deflector rolls 32 to impregnate the tapes with resin. Alternatively, the impregnation may take place by spraying resin into the forming zone 31a of the tool. The resin may, for example, consist of the previously exemplified unsaturated polyester resin. In addition to the forming zone 31a, where the profile is created, the tool has a curing zone 31b, where the impregnated product is cured. The pulling rate and the heating conditions are selected so that the profiled product 33 is completely cured when it leaves the curing zone. The advance of the tapes through the tool 31 takes place by traction generated on the cured product 33 by means of a roll pair 34. The profiled product 33 of reinforced plastics material can be cut into suitable lengths by a cutting machine 35.

In Figure 4 the tape 1 1 a is indicated by a dashed line before it is impregnated and before the resin in it has been cured after its impregnation, whereas the cured product, reinforced with the tape, is indicated by a continuous line.

Claims (15)

1. A method of manufacturing a reinforcing tape comprising mutually parallel warp threads and, transverse thereto, mutually parallel weft threads, which method comprises leading a tape with the warp and weft threads at right angles to one another into the nip between an opposed pair of rollers, deflecting the warp threads of the tape laterally downstream of the nip through an oblique angle while leaving the weft threads downstream of the nip substantially parallel to the weft threads upstream of the nip and maintaining the new orientation of the weft and warp threads to form the reinforcing tape.

2. A method as claimed in claim 1, in which the maintaining of the threads in the new orientation is effected by winding the tape onto a winding-up device rotating about an axis normal to the warp threads.

3. A method as claimed in claim 1, in which the maintaining of the threads in the new orientation is effected by impregnating the fibres of the tape with a resin material downstream of the nip.

4. A method as claimed in any preceding claim, in which the oblige angle through which the web is deflected is substantially equal to the new orientation between the weft and warp threads.

5. A method as claimed in any preceding claim, in which the new orientation of the weft and warp threads is 45".

6. A method as claimed in any preceding claim, in which the weft threads are considerably thicker than the warp threads.

7. A method as claimed in claim 6, in which the warp yarns have a thickness of a few tens of tex and the weft yarns a thickness in excess of one thousand tex.

8. A method as claimed in claim 7, in which there are some four warp yarns per centimetre and substantially half that number of weft yarns per centimetre.

9. A method of manufacturing a fibre-reinforced product of plastics material which comprises embedding at least one reinforced tape as produced by application of the method of any preceding claim in a mass of hardensable plastics material and allowing the material to harden in the required shape to give the product.

10. A method as claimed in claim 9, in which the shaping of the material is effected by winding tape impregnated with the hardenable plastics material onto a mandrel.

11. A method as claimed in claim 10, in which alternate layers of tape have the weft and warp threads perpendicular to each other.

12. A method as claimed in claim 9, in which the shaping of the material is effected in a die former through which tape impregnated with the hardenable plastics material is drawn.

13. A method of manufacturing a reinforcing tape substantially as hereinbefore described with reference to, and as illustrated in, Figure 1 or Figure 2 of the accompanying drawing.

14. A method of manufacturing a fibrereinforced product substantially as hereinebfore described with reference to Figure 1 or 2 in association with Figure 3 or Figure 2 in association with Figure 4 of the accompanying drawing.

15. A reinforcing tape made by the method of any of claims 1 to 8.