FI109923B - Resin-reinforcing fabric prodn. - Google Patents

Abstract

Producing resin-reinforcing fabric contg. reinforcing strands of glass, carbon, aramid, borax or ceramic, involves binding the reinforcing strands in channels between two interconnected knitted fabric layers, each layer having single knitted loops, but with loops of one layer on the opposite side of the fabric to the loops of the other layer, (i.e. the latter loops are wrong way round), specifically by dial needles of a circular machine. Pref. one layer is knitted, the reinforcing strands are laid upon it, and the second layer is knitted to the first layer as one course upon another progressively.

Description

109923

DIRECTED FIBER STRUCTURE AND METHOD FOR MANUFACTURING IT

The invention relates to a directional fiber structure according to the preamble of claim 9 and to a method 5 for its manufacture according to the preamble of claim 1. Laminate is generally referred to herein as various fiber composites. The invention is also intended for use in ballistic protection and cut protection.

According to the prior art, fiberglass laminate is made by applying a resin to the fiberglass mat placed on the mold surface. The glass fibers can be bound as staple fibers to a glass fiber mat or woven into a warp structure. The disadvantage of these is that air bubbles tend to remain in the laminate. The phenomenon is particularly difficult at the corner. From German application DE 3.304.345, a warp structure for laminating is known. U.S. Pat. No. 3.201.194 discloses a circular knitting machine for bonding a metal wire for reinforcing a pipe into a knit. However, there are quite a few 20 nets here. If the knit is pulled tight, the reinforcing yarn or the reinforcing fiber will not remain straight, making it unsuitable for example for fiberglass which loses its strength when bent.

GB 1258238 discloses a laminated warp structure. Warp knitwear and their manufacturing methods differ significantly from the weft knitwear of the present invention.

I I 1 • · »·. ···. GB 2121837 discloses double-sided knitwear. for the garment industry, in which the knitwear has in-lay- 30 threads for decoration.

It is an object of the present invention to provide a novel, particularly laminable, fibrous structure which is easily deformable on the mold surface and which avoids the aforesaid air bubbles of the laminate. It is also advantageous to use *: · so-called. The prepreg or commingled process, wherein the binder is incorporated into or adjacent to the support fiber, whereby, upon heating, knit 2 109923 cures to a thin shell structure. One binder may be polyester fiber.

Because the backing fibers are often a resilient material, the knit ve-5 must be piled up, whereby the non-resilient reinforcing fibers protrude from the knit. This can be controlled by the method of claim 8, which leaves holes in the knit at regular intervals to allow the reinforcing fiber to protrude.

The main advantages of the invention are listed as follows: a suitable choice of material for backbone filaments and reinforcing fiber filaments achieves very low specific gravity; , whereby directional fiberglass filaments with good strength properties 20 can be easily placed to carry most of the load that the laminate is designed to withstand, • · - a knit element with directional reinforcing fibers is *. · · flexible and flexible in all directions, min. j V-shape is easy, - the tubular knit element can be easily cut ii ·::: both open in the transverse direction with respect to the oriented reinforcing sleepily, allowing the knitting element to be used as a sheet element of the desired shape and / or size.

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It is also an object of the invention to provide various protective purposes. fiber structure. It is a further object of the invention to provide a method of manufacturing a fibrous structure suitable for any fiber to be oriented.

3, 109923

The main features of the process of the invention are apparent from the appended claim 1. The main principle of the invention is to bind the reinforcing fibers to a double-sided flexible knit in the transverse direction with respect to the loops. Furthermore, the invention enables, firstly, a high production efficiency and, secondly, the production of a product according to claim 10. Such a tubular fibrous structure is particularly advantageous when, when laminated, it can be directly pulled over the tube, pin or the like. Generally, both backbone and reinforcing fiber are filamentous or endless.

By the method of claim 2, the reinforcing fibers can be dense knitted. The embodiment 15 according to claim 3 has the particular advantage that, if the resin is effectively absorbed into the knit, bubbles are unlikely to occur. Most reinforcing fibers do not withstand any knots at all. On the other hand, the strength of the aramid fibers remains moderate even when folded, whereby the entire fiber structure can be knitted with this fiber. Keh-20 ragged fiberglass is also tested like aramid.

Naturally, several reinforcing fibers, i.e. bundles of fibers, can be used instead of a single reinforcing fiber. On the other hand, it is not necessary to insert reinforcing fibers at each loop of its V · loop.

* · /. · 25 In this context, it is mentioned that the reinforcing fiber can be a problem The measure uses any known fiber, for example: glass, carbon, aramid, boron and ceramics *: fibers in the form of filaments or bundles. Polyamides and their derivatives may also be used as reinforcing fibers.

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In the following, the invention will be illustrated by way of example with reference to the accompanying drawings, on ice

Figure 1 is an enlarged view of a knit according to the invention. Figure 2 shows another knit enlarged. · '· 35 Figure 3 shows a third knit enlarged

Figure 4 shows a tubular knit 4 109923

The knit of Fig. 1 is provided with a so-called "knit". with a double circular knitting machine with vertical needle cylinders and horizontal needle needles. Generally speaking, there is a first needle and a second needle, one of which knits 5 upside down and the other of a needle upside down. Polyester or other fiber is used as the support fiber 7, i.e. the loop filament. The cylinder-side knitting needles are inserted to a feeding system loops 2. Lautaspuolen the needles are inserted the other hand, so-called. interlock setting, where in successive 10-sided feeds the knitting takes place alternately. The loops knitted by the disc needles are denoted by reference numerals 3 and 4. The reinforcing fibers 1 are fed by every other system and remain in the channels formed by the misaligned loops 2,3,4. The reinforcing fibers 1 remain in the knit 15 transversely of the loop stitches 10. Thanks to the Interlock setting, the knit tends to retract longitudinally, making the reinforcing fibers very dense.

Potential protrusion of the reinforcing fiber can be controlled by removing the needles from the disk needle at regular intervals, whereby the reinforcing fiber protrudes from the resulting openings. Such a knit also offers surprising advantages when laminating. Outward V 1: Due to the protruding fiber loops, the fibers have a triaxial * · / ·: social orientation, which prevents the rigid structure from being broken apart, i.e. the layers are separated.

:: Obviously, the fibrous structure may differ from the above. However, the knit should have loops formed in both directions, "right" and "inside out", between which the reinforcing fiber can be guided. The reinforcement fibers can also be knit in very few smooth knitwear .1. Closed.

. Existing circular knitting machines have cylindrical diameters ranging from 5/8 "to 36". Larger machines can efficiently make a wide fiber mat, since the sock can be loosened and spread on the mat. For example, a 2.8 "wide nonwoven fabric is provided with a 36" machine. When laminating, the various layers can be cross-linked for equal strength in all directions. On the other hand, tubular products are particularly easy to laminate with the available tubular fibrous structure. the direction is just right, for example for pressure loads.

In another preferred embodiment of the invention, the reinforcing fibers 1 in the knitting element 10, as illustrated in Fig. 2, are rarely traversed directly and parallel to each other in a row of loops 11 and 12 supported by the top and bottom the knitted loop stitches 10, so that in the loop row 11,12 containing the supporting fibers 2, each correctly knitted upper loop 14 always closes down one of the supporting yarn filaments 1. To obtain such a supporting filament order, and 3/4 the corresponding number of loop filaments that are guided from the feeding points spaced evenly around the circumference of the needle. When the system number: 36 is mentioned above, there are 9 staple fiber filaments and::: 25 there are 27 staple fiber filaments: Thus, in the knitted element produced: thus, some of the first and second stitch rows 11,12 are knit together without interlacing. Silmukkava-; in the direction of the knots 10, each stitch rib 11,12 containing the support fiber 1 is followed by at least one sil-30 pattern free from the support fiber filament.

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Figure 3 further illustrates the needle according to a third preferred embodiment of the invention, already mentioned above. a lozenge element formed in accordance with another embodiment of the invention, with the exception that several, i.e. 3, parallel filament filaments are deposited at a single feeding position on the first row of loops 11 6 109923 knitted with a single needle fiber. Thus, each row of loops 11,12 containing a plurality of parallel support fibers 1 is followed, in the direction of the loop ridges 10, by two lines of free loops of support fibers 5. Similarly, binder fibers can be counted with the reinforcing fiber.

Figure 4 shows a tubular knit 5 which provides a strip-like fibrous structure. The tubular knit 5 is left with 10 narrow strips 6 to which no reinforcing fiber is fed at all. At this strip 6, the knit can be easily cut open to obtain said ribbon-like product. Figure 4 clearly shows that the loop holes 10 extend in the longitudinal direction of the tubular knit whereas the reinforcing fibers 1 spirally run around the knit.

In one test knit, the ratio of glass fiber to polyester filament was about 50/50. This resulted in a low specific gravity of the laminate of only 1.3 g / cm3. The calculated density of a hollow sphere with a diameter of 100 mm and a hollow sphere of 2.5 mm with a wall thickness of 20 mm would be approximately 0.2 g / cm 3 for this laminate.

In particular, for aramid fibers, a process may be applied whereby this fiber is first treated so as to obtain, at rest, a helical or tortuous shape of V 25: in the finished product: it tends to pull it together. In this way the knit • · *:> i§: is also elastic in the direction of the reinforcing fibers.

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Claims (13)

A method of manufacturing an oriented fiber structure for lamination, in which reinforcing fibers (1) are bonded to an oriented fiber mat or corresponding knitted element, with which the fibers (1) are laminated within resin or other binder and thus form a strong shell structure. by making the knitting on a so-called double circular knitting machine in such a way that the knitting comprises successive and continuously repeated manufacturing steps: a) the first stitch (2) is made with the first needle set, b) at least one reinforcing fiber (1) for to fit into the knit »1 · v 'the fabric is oriented and placed on the top of the above! 'said, first mask, and j': c) a second mask (3, 4) is knit with the second needle-piece: '' on the top of the oriented reinforcing filament and attached to the above-mentioned first mask (2); the oriented reinforcing fiber (1) preferably supported by the ·; ··· stitches (2, 3, 4) and straight in the channel delimited · 2 ′; Between the mesh rows (11, 12) formed in this way. IΓΓ 2. A method according to claim 1, characterized in that the nails on the cylinder side are mainly arranged to knit in each step and: .1 the dial or corresponding nails are arranged to reciprocally · .1 ·; 35 passing, i.e. they are set for so-called interlock positioning, so that the knitted fabric will contract in the longitudinal direction. 3. A method according to any one of claims 1 or 2, characterized in that polyester or other fiber which readily absorbs resin is used as carrier fiber (7). 4. A method according to any of claims 1 to 3, characterized in that more than one fiber (1) is laid parallel to the top of the first row of meshes (11). 5. A method according to any one of claims 1 to 4, characterized in that some of the mesh rows (11, 12) are knit together without the above-mentioned fiber fibers being laid between them. 15 6. A method according to any of claims 1-2, characterized in that aramid or spun glass fiber is used as carrier fiber (7). 7. A method according to any one of claims 1 to 6, characterized in that the carrier fiber contains laminating adhesives which are reacted by heat or in some other way, and which then make it possible to produce a strong shell structure with the same. 'called the pulp method. j ': 25 8. A method according to any of claims 1-5, characterized in that one: nails have been removed from one side at regular intervals,: most preferably from the rib side, so that the reinforcing fiber is made to protrude from the thus formed openings in the knitted ·; · * : chewed. 30> s 9. Oriented fiber structure for lamination in which reinforcing fibers (1) are bonded to an oriented fiber mat or corresponding knitted element with which the fibers (1) are laminated II: inside resin or other binder and thus form a strong shell structure , characterized in that the reinforcing fibers (1) in the transverse direction are bonded to the smooth knitted fabric with the straight stitches (2) by means of the stitched stitches (3, 4). 10. Knitted fiber structure according to claim 9, characterized in that the knitted fabric (5) is tubular and the reinforcing fibers (1) preferably in a continuous spiral around the knitted fabric (5). 11. Knitted tubular fiber structure according to claim 10, characterized by a narrow spiral strip (6) without reinforcing fibers (1) 10 between the spiral reinforcing fibers (1) so that the tubular knitted fibers (5) can be cut up to form a band. Fiber structure according to any of claims 1 to 11, characterized in that the reinforcing fibers, for example aramid fibers, are wound in a ring so that the fiber structure becomes elastic even in the fiber direction. <· • · • «» • 1 1 • 1 · • I · • · »I · M || • · • · *