DE102004014325A1 - Complex mat with a layer of volumised fibers - Google Patents

Abstract

Process for producing a multilayer mat formed with the aid of fibers, spun yarns, yarns or threads, a multilayer mat produced in accordance with the method or a molded part produced therefrom, and a device for carrying out the method.

Description

The The invention relates to a process for the preparation of an aid of fibers, spin threads, Yarn or twisted formed, multilayer mat, a method according to the production multilayer mat or molding produced therefrom and a device to carry out of the procedure.

A made of glass fibers is used in the DE 203 10 085 U1 described. This clutch consists of loosely laid fibers that were not sewn together.

A multilayer mat of the type mentioned should have a high ductility and a high three-dimensional deformability, if they are to be used for the reinforcement of curable plastics. These mats, for example, according to the publication EP 0 395 548 B1 embedded between two mold halves. After closing the mold halves, resins (such as unsaturated polyester resins, phenolic resins, epoxy resins) are placed in the open cavities of the molds by injection (pressure) or infusion (vacuum). The result is a so-called full laminate.

Consists the middle layer of a multi-layer mat made of a particularly lightweight Material such as foam, so there is a so-called sandwich - laminate in front.

In principle, several individually inserted fiber layers can be used for pressing in such closed systems. Advantageously, however, multilayer mats are processed, as these from the publications DE 100 51 598 A1 such as DE 102 11 175 C1 are known. The workflow can be simplified and made cheaper.

Out have the aforementioned prior art multilayer mats two outside Cover layers of cut glass fibers. In the core area there it's a middle layer. The individual layers of these mats are through a stitching process connected to a multilayer mat.

For the function of this multi-layer mat, it is important that the middle layer, also called middle layer or core layer, behaves elastically and restoring tension to provide. Then it can be achieved that these resilient Middle position the outside lying cover layers reliably press the molds. This ensures that it is between the shape and the cover layers not to rinse off not reinforced Resin comes, what the functionality would affect the produced molding. The multilayer mat should be stretchable at the same time, so that with complicated shaping it does not lead to material cracks.

Commercially available Multilayer mats comprise a central or core layer of needled or felted plastic monofilaments (e.g., polypropylene, polyester, Polyamide, etc.) or from needled or looped knit Glass fibers. The middle layer is served with cut reinforcement Fibers occupied from both sides and by a Nähwirkprozess preferably loosely connected. So should the stretchability and deformability the multilayer mat and the restoring tension of the core material guaranteed become. At the same time caused by the existing reset voltage of the core material, ie the middle layer of open drainage structures, the after closing the shape of the vent and stuffing with liquid Resin as possible little affect.

These are on the market as well as from the pamphlets DE 100 51 598 A1 such as DE 102 11 175 C1 However, known multilayer mats, which are offered for example under the name ROVICORE or MULTIMAT, have the disadvantage that when using plastic filaments for the core layer, the laminate homogeneity of the finished molding is disturbed because these plastic filaments between the actual Verstärkungsfasem as Foreign body form a separate separation layer. There are problems in terms of strength in the molded article produced therefrom.

at Use of loop-shaped formed glass fibers, the problem is that in the forms compressed multilayer mat, also called complex material, due to the high material compression to much higher specific Weights stir, than this for most moldings desired becomes.

The Embodiments known from the prior art also have the disadvantage that at low compression in the form it too very high and unwanted Resin enrichment in the core area occurs and too high compression vent and flow rate is disadvantageously greatly reduced.

Out WO 02/076701 A1 discloses a multilayer mat which in which the volumised spin threads formed from fibers, yarns or twists of a middle layer by the material or the degree of Differentiate volumization. It should have such good drenching and venting properties be achieved with low resin absorption.

The object of the invention is to provide a multilayer mat as well as herge presented moldings with improved properties.

To achieve the object, a multilayer mat is provided in which the middle layer comprises volumised spin threads, yarns or threads. Volumised spin threads, yarns or threads are used in the DE 3540537 A1 described. Hollow body fillers made of plastic are embedded between fibers of spin threads, yarns or threads. In particular, the hollow body fillers are hollow microspheres that have been previously inflated by the application of heat. The unexpanded precursor of a hollow body filler is introduced for this purpose in the interstices between the fibers and exposed the material thus obtained for the required duration of a temperature required for the blowing process of the precursor.

Of the Diameter of the hollow body fillers is typically 20 to 300 μm. The length the fibers used, spin threads, Yarns or threads is advantageously 5-150 mm.

At the In the prior art, volumization is provided to increase the capacity for liquid curable resins on a desired Value to be able to adjust. In contrast, with the present invention, the goal pursues and achieves the mechanical properties of a multi-layered To improve mat and especially for good elastic properties as well as reset voltages to care.

Especially For example, filaments, yarns or threads made of glass fibers are volumized. It will be so formed from glass fibers spun yarns, yarns or threads to a multiple of their original one Volume expands. These now become a multi-layered mat with outside lying top layers processed. The outer cover layers may be off Fibers and in particular glass fibers exist, for example through a stitchbonding process be connected to the middle layer. The cover layers are preferred but also from Spinfäden, Yarns or plying formed, since then the production easier is.

The Manufacturing is done easily and inexpensively by using several consecutive arranged cutting units the individual material layers on one Treadmill layered filed and the Nähwirkprozess supplied become.

One Disadvantage of the multi-layered mats on the market, Also called complex mats, namely, is that the needled or knitted middle layers, also called core layers, in a separate machine working process must be produced. The multilayer inventive Mat can be produced in one go on a machine. A cheaper one Production in comparison with the prior art is therefore possible.

It was surprising found that even two-dimensionally arranged, with elastic micro hollow bodies or balls expanded fiber strands a high elasticity and reset voltage and to generate a high hydraulic backpressure on pressure, the is achieved by the deformation of the micro hollow body. This Back pressure is sufficient to outside lying, the reinforcement serving fibers to the mold walls to press. In contrast, it comes in the market and core layers described above only to mechanical springback effects, if a part of the needled or looped knitted or knitted Fibers or spin threads, yarns or twisting wires are arranged vertically in the direction of pressure (three-dimensionality). Both voluptuous spin threads, On the other hand, yarns or threads surprisingly reach the two-dimensional arrangement to advantageously a high reset voltage to be able to provide.

A Although mat used as a middle layer can also be subsequently volumisiert become. Such mats have been around for some time under the name "SPHEREMAT" on the market have by the chemical or mechanical fixation in the crossing points not the desired one flexibility and extensibility of loosely superimposed and only after the Sewed volumization Strands, Yarns or threads. Therefore, the use of such is preferable Mid layers made from already voluptuous spin threads, yarns or threads were.

at the three - dimensional arrangement of the spin threads, yarns or threads of the Core or middle layer of the multilayer on the market Mats ("ROVICORE", "MULTIMAT" etc.) are in vertical direction produces compressive stresses that are unsightly surface lead the finished molding (Print effect). Become the volumisierten spin threads, yarns or threads one Core or middle layer arranged two-dimensionally, these become impairments the surface avoided a molded part.

The embedded hollow microspheres also reduce resin consumption up to 50% compared to those mentioned, available on the market multilayer mats. This means a reduction of the specific Weight of partially more than 50% unlike on the Market complex mats.

Due to the hydraulic reset of the hollow microspheres and despite the zweidimensio only The random arrangement of the volumised spin threads, yarns or threads results in a coarse and open material structure. This leads to advantageous venting and resin drainage properties.

One Another advantage when using very light and low-resin voluminized filaments consisting of glass fibers. Yarns or plying in the Core of a multilayer mat is that the Result the characteristic of a full laminate, but the weight reducing Properties of a sandwich laminate Has. Unlike the sandwich laminates already on the market no extra Core material made of light wood or foam and the like separately be incorporated if, for structural reasons, a light, rigid Construction desired becomes.

Advantageous Both the core layer or middle layer and the cover layers exist or cover layers of glass fibers. It can be such an unprecedented homogeneity to achieve the product. The physico-mechanical properties the middle class then corresponds to the physical-technical properties the cover layers.

1 shows a section of the middle layer in a plan view and 2 a section of the middle layer from a perspective. Between individual glass fibers 1 are spherical hollow bodies 2 embedded. The gaps 3 can be filled with impregnating resins. 3 shows schematically the construction of a multilayer mat. Two cover layers 5 and 6 , which consist of non-volumised glass fibers, close a middle layer 4 one formed of voluminized filaments made of glass fibers. The fibers in the cover layers 5 and 6 as well as in the middle position 4 are parallel or at least nearly parallel to the surface 7 and are arranged two-dimensionally in this sense.

The manufactured, in 3 schematically shown complex mat consists of cut fibers with a cut length of 5 - 200 mm. The different layers have been joined together by a stitchbonding process. The outer layers 5 and 6 consist of cut glass fibers and the middle layer 4 from volumised, cut filaments formed from glass fibers. The core situation 4 may be a mixture of voluptuous filaments, yarns or twists and non-volumised glass fibers. For the volumised situation 4 Fibers based on carbon, aramid and plastic fibers have proven to be particularly suitable. The outer layers 5 and 6 then preferably consist of aramid or carbon fibers. The spin threads of the middle layer have been cut after volumizing and then joined to the cover layers by a stitchbonding process.

An apparatus for carrying out the method is shown schematically in the 4 shown. Above a treadmill 8th are three reapers 9 . 10 and 11 arranged one behind the other. The outer cutting units are fed with so-called endless spindles, which are not volumised. The middle cutting unit 10 are fed volumisierte endless spin threads.

One Endless thread is one that is very long and usually for the Processing is handled by a spool. Such an endless thread can have several ten meters to several hundred meters long.

The cutting units cut spindles of the desired length from the endless filaments. The cut threads reach the underlying treadmill 8th , The treadmill 8th transports layered superimposed, cut filaments to a facility 12 Sewing the spider threads together. As a result, then lies in 3 shown mat.

Claims (12)

Method for producing a mat with the steps; Providing a layer ( 4 ), the volumised spin threads, yarns or threads ( 1 . 2 ), - providing at least one further fiber-formed layer ( 5 . 6 ), - connecting the layers ( 4 . 5 . 6 ), preferably by sewing. Process according to Claim 1, in which non-volumized and volumised spin threads, yarns or threads are laid on top of one another in layers, preferably on a treadmill and subsequently the layers ( 4 . 5 . 6 ) are sewn together. Method according to the preceding claim, in which the fibers or spin threads, yarns or threads formed therefrom Cutting of continuous fibers, continuous filaments, continuous filaments or endless twists be filed. Method according to claim 1, 2 or 3, wherein the layers ( 4 . 5 . 6 ) are formed by fibers, spin threads, yarns or threads parallel to the surface ( 7 ) of the mat are arranged. Method according to one of the preceding claims, in which the fibers, spines, yarns or threads provided for the layer construction are 5 to 200 mm long and / or the hollow micro-bodies used for the volumizing have a mean throughput have knives of 20 to 300 microns. Method according to one of the preceding claims, in the middle layer and cover layers are made of glass fibers. Method according to one of the preceding claims, in the mat is placed in a mold and mold-curable resins for producing a fiber reinforced Be brought molding. Mat manufacturable by a method with the features according to one of the preceding claims, comprising a middle layer of volumised spin threads, yarns or twisting as well as cover layers of non-volumised fibers, the sewn together are. Mat according to the preceding claim, in which the fibers, spin threads, yarns or threads are parallel to the surface ( 7 ) are arranged. Mat according to one of the two preceding claims, at the fibers, spin threads, Yarns or threads exclusively are made of glass fibers. Apparatus for producing a mat according to one of the three preceding claims, consisting of three successively arranged cutting units ( 9 . 10 . 11 ) above a treadmill ( 8th ), as well as means for sewing ( 12 ) on the treadmill ( 8th ), from the cutting units ( 9 . 10 . 11 ) coming cut fibers, spin threads, yarns or threads. Device according to the preceding claim, at the filament yarn, yarns, volumized in the center of the cutting unit or twisted and the two other cutters not volumisierte spin threads, yarns or Twisted are.