EP4001480A1 - Thread structure - Google Patents

Abstract

The invention relates to a thread structure (1) with thread bundles (2, 3, 4) laid parallel to one another; (2', 3', 4'); (2", 3", 4"), which are composed of individual threads (5) and are laid so that they cross one another, forming distances transverse to their respective laying direction from the respective adjacent thread bundle, with only the thread bundles (2,3,4 ); (2',3',4'); (2",3",4") are provided with a thermoplastic matrix (6) in the manner of a composite material while leaving the spaces (7,8) between them free. A prepreg end product is also specified which has holes defined by longitudinal and transverse dimensions which are located between the individual bundles of threads (2, 3, 4); (2', 3', 4'); (2", 3", 4") are located.

Description

The present invention relates to a thread structure according to claim 1. Prepregs are well known.

the DE 69003875T 2 discloses a prepreg consisting of warp yarns and weft yarns, with the weft yarns running obliquely to the direction of the warp yarns. This structure is created for a specific carrier and is not changed anymore.

the U.S.P.S. 5,53 6,554 discloses a belt of reinforced construction. The individual reinforcement elements have different laying directions.

the US2005/0085147A1 discloses a prepreg woven from bundles of fibers with gaps between the bundles filled by auxiliary yarns to prevent openings in the final product.

The object of the present invention is to produce such prepregs with an increased utility value in a simple manner, while ensuring that the composite structure stabilizes the end product uniformly over the entire flat design of the end product.

The invention solves this problem with the features of the main claim.

The advantage of the invention is that such a thread structure can be produced in the simplest way, practically as a raw fabric, in open form, which already has a dimensionally stable structure a priori, because the thermoplastic matrix in the individual thread bundles not only stabilizes the thread bundles, but also the entire thread structure.

It is essential that the thermoplastic matrix is present in a volume which, in a subsequent pressing process under the known influencing factors of pressure, temperature and time, can flow into the gaps provided between the individual bundles of threads during production and in this way in this subsequent pressing process for a uniform Laying of the individual threads in the end product ensures.

It is therefore an essential idea of the invention to determine the distances between the individual laid bundles of threads, which each run parallel to the direction and form distances between them in the transverse direction, so large with regard to the thermoplastic matrix present in the respective bundle of threads that this thermoplastic matrix together with the Pressure from each bundle of threads flowing outwards forms a composite body evenly interspersed with individual threads in every direction, which is also interspersed with the thermoplastic matrix over the entire longitudinal and transverse dimension due to the excess thermoplastic matrix provided by the manufacturer.

This is a major advantage of the invention, because the invention has recognized that the flow process of the individual threads in the originally existing free areas between the thread bundles produces practically homogeneous material properties in every direction, so that corresponding material parameters such as tensile strength, etc. can also be guaranteed.

It is particularly advantageous that the dimensioning of the thread bundles, ie their cross-sectional dimensions and the associated free points between the Thread bundles can be easily matched to the respective end product.

Of course, the open lattice structure applies in all directions that are transverse to the respective laying directions of the direction-parallel thread bundles.

The thread structure according to the present invention can be produced as a semi-finished product, sandwich or lightweight board.

In any case, the penetration of the thermoplastic matrix through the entire bundle of threads is essential. This means that practically no air pockets should be allowed in the thermoplastic matrix, at least not in the technically feasible range, so that the flow of the matrix in the downstream process can also lead to a full-volume matrix portion in the end product.

In the downstream process, an additional thermoplastic material can also be processed easily, so that thanks to the invention, anchoring this additional thermoplastic material on both sides as a result of penetration through the plastic matrix present in the original prepreg leads to an improvement in the material properties.

It is of course recommended to use plastics that are compatible with the original plastic of the prepregs.

In this respect, the invention offers the additional advantage that, in the second processing step, a lower pressure is sufficient to bring the thermoplastics together in a capillary bond.

This is achieved in particular in that the elements already present in the original thread bundles are saturated with a thermoplastic matrix and therefore the thread structure present in the end product only has to be contacted by the additionally used thermoplastics only in the microscopic range under a pressure that only produces the capillary bond.

In this context, the injection technique for injecting thermoplastic material into the originally present thread bundles also attracts attention.

The thermoplastics used today have well-known kinematic state variables that can be set in such a way that each individual bundle of threads can be completely saturated so that later end products no longer have any air pockets.

The invention thus shows that, hitherto unknown, it can also have constant grid values in the structure of the end product, so that reliable predictions can be made with regard to the material properties.

Since the invention basically has holes defined by longitudinal and transverse dimensions in all embodiments, which are located between the individual thread bundles, at least before the thread bundles are pressed in a further processing step under the influences of temperature, pressure and time, such a thread structure can also have its Grid values are defined.

Grid values are those parameters that define the size of the gaps between the thread bundles, for example the X or Y values in a Cartesian coordinate system.

This applies accordingly in the case of multidirectionally laid thread bundles.

In addition to the anchoring in the capillary network, a possibility for chemical anchoring of the subsequently used thermoplastics and the already mentioned possibility of changing the thread geometry with regard to the structure of the end product is of particular advantage.

Advantageous developments of the invention result from the dependent claims.

Only two directions, preferably crossing one another perpendicularly, can be provided for the thread bundles.

Depending on the requirements of the end product, it can also be advantageous to provide more than two directions. Exemplary embodiments are given for this.

In any case, however, it is of essential importance that in each thread bundle there are at least as many layers of individual threads and as much thermoplastic matrix that the lateral spaces between the thread bundles present in the original thread structure are filled by the individual threads flowing into the adjacent lateral spaces that were originally left free.

The manufacture of the thread structure as a roller conveyor offers the lowest costs per unit of length in terms of production technology and, in particular, the possibility of preparing the roller conveyor in the form of blanks for further processing.

The invention is explained in more detail below using exemplary embodiments.

Show it:

Fig.1

the basic principle of the invention;

Fig.2

a three-dimensional view of the invention, here in the form of a fabric;

Fig.3

an enlarged view of a thread bundle;

Fig.4

an arrangement of thread bundles laid in more than two parallel directions;

Fig.5

schematic representation of the flow process;

Fig.6

Presentation of the thread structure, cutting, end product.

Unless otherwise stated below, the following description applies to all figures.

The figures show a thread structure 1 with thread bundles 2,3,4; 2',3',4'; 2",3",4".

It is essential that there are distances between the respective parallel laid bundles of threads in a direction transverse thereto, in which there is no material at all, and this in each case transversely to all laying directions in which the respective bundles of threads are laid.

It is an open fabric, but a non-crimp fabric is also possible or another form of the respective flat end product of the thread structure without restricting the invention to this.

To this extent, the invention also applies, for example, to unidirectionally laid bundles of threads in which only transversely there are significant distances within the meaning of the invention to the direction of the laid thread bundles.

In this case, bundles of threads laid unidirectionally could be fixed to one another by occasional transverse auxiliary threads.

From this product of the thread structure, a wide variety of prepared components for all possible industrial applications can be manufactured in a downstream process, for example by injection molding or forming.

It is essential in this respect that the thread structure is completely and evenly impregnated with a thermoplastic matrix in a form-fitting manner and that the thread bundles can no longer move relative to one another after the thread structure has been correspondingly pre-consolidated. Pre-consolidation in this sense means that dimensional stability of the lattice structure with the openings located therein must be achieved.

This is state-of-the-art by production processes known per se, such as the production of a non-crimp fabric, a fabric or the like.

How in particular Fig.3 shows the thread bundles 2,3,4; 2',3',4';2",3",4" completely penetrated by the thermoplastic matrix 6.

Each bundle of threads consists of a large number of individual threads 5, which are shown and embedded in the full-volume thermoplastic matrix.

The thermoplastic matrix present in each thread bundle at the connection points of the fabric/layer connects the thread bundles crossing in pairs in a dimensionally stable manner with each other, so that semi-finished products made from the thread structure can be cut to fit the respective end product as required.

This offers the advantage that it is easy for the end user to position the semi-finished product precisely as a blank in the end product without the basic structure of the non-crimp fabric/fabric changing during further processing.

In order to achieve a homogeneous laying pattern of the respective thread bundles in the end product, it is proposed that the thread bundles have the same width and the same thickness in every direction.

It is proposed for one embodiment that the woven or non-crimp fabric constructions have a thread spacing of more than 2 mm and, depending on the profile of requirements for the end product, are arranged biaxially and/or multiaxially at right angles and/or in different directions.

However, this is not a limitation of the invention. In this respect, all technically sensible lattice structures with corresponding longitudinal and transverse dimensions of the distances between the thread bundles are also covered by the patent claim.

How in particular Fig.3 also shows that each bundle of threads has individual threads 5 arranged in multiple layers, which are distributed more or less evenly in the bundle of threads and are enclosed flush and completely by the thermoplastic matrix.

For this reason, the thread bundles have a width 9 and a height 10, so that so many layers of individual threads can be accommodated in each thread bundle and so much thermoplastic matrix can enclose these individual threads that when the thread structure is pressed under the known parameters Pressure, temperature and time, the originally existing distances 7.8 between the individual thread bundles are filled by flowing the individual threads 5 into the adjacent originally released distances 7.8.

In this process, it is essential that in the process of post-processing for the production of the end product 14 so much pressure, temperature and time is exerted on the originally existing structure that the existing thermoplastic matrix moves at least into the originally released distances 7, 8, taking with it the in you can crush embedded individual threads 5, so that in the end a three-dimensionally shaped end product is created with evenly embedded individual threads originating from the original thread bundles.

In addition to this, the Fig.6 the presentation of the thread structure according to the invention as a roller conveyor 12, which can be used, for example, for the production of blanks 13, which can be processed as an end product after corresponding 3-D deformation, here for example as a can lid 14.

Furthermore, it should be expressly mentioned that the thread structure can also be produced in the form of a presentation with a carbon look in order to be able to serve corresponding customer groups if necessary.

The invention has also made it possible to surprisingly find that not only thermoplastics can be used alone, but also duroplastics.

This was particularly evident in the case of thermosetting plastics of only a small thickness, since these remain elastic during curing, provided the thickness is correspondingly small.

Furthermore, the invention also relates to a method for producing the thread structure according to the invention, which has proven to be advantageous.

In this method, which applies to all of the exemplary embodiments already mentioned, first of all an intermediate structure of a flat structure, such as a woven fabric or a non-crimp fabric, is produced, with the thread bundles being laid according to the subsequently desired thread structure.

A liquefied plastic, which can be either thermoplastic or duroplastic, is then applied to this intermediate structure so generously that the excess plastic has to be removed after exposure.

In this case, however, this excess plastic is only removed to the extent that each bundle of threads remains fully interspersed with the remaining plastic to fill the volume.

This ensures that each individual thread bundle forms a composite material with a plastic matrix that is practically free of air inclusions and in this way gives the thread structure considerable strength properties in every main direction of the laid thread bundles.

While the originally liquefied plastics are still liquid, the undesired excess amounts are mechanically or aerodynamically removed from the intermediate structure by suitable measures.

This can be done, for example, via pairs of rollers or transverse blowing streams.

After that, the mandatory holes between the individual thread bundles are free at least once.

If the originally liquefied plastic has not dried yet, it is recommended to subject the lattice structure prepared in this way to subsequent drying. This can be done without contact, for example by infrared heating or the like in an oven or under an infrared radiator, so that the dried finished product can then the thread structure according to the invention, can be rolled up so as to become roll dressing.

Surprisingly, it has been shown that a thread structure interspersed with duroplastic plastic can also be rolled up.

The low thickness of the thermosetting plastic on the thread structure allows for a high level of flexibility without the risk of breakage, although it is a thermosetting plastic.

Reference List

1

thread structure

2

Bunch of threads, horizontal

3

bundle of threads

4

bundle of threads

2'

Bundle of threads, vertical

3'

Bundle of threads, vertical

4'

Bundle of threads, vertical

2"

Bunch of threads, diagonal

3"

Bunch of threads, diagonal

4"

Bunch of threads, diagonal

5

monofilament

6

thermoplastic matrix

7

distance between 2,3,4

8th

Distance between 2',3',4'

9

Broad

10

thickness

11

flow process

12

roller conveyor

13

cutting

14

can lid

Claims (14)

Thread structure (1) with thread bundles (2, 3, 4) laid parallel to one another; (2', 3', 4'); (2", 3", 4"), which are composed of individual threads (5) and are laid so that they cross one another, forming distances transverse to their respective laying direction from the respective adjacent thread bundle, with only the thread bundles (2,3,4 ); (2',3',4'); (2",3",4") are provided with a thermoplastic matrix (6) in the manner of a composite material while leaving the spaces (7,8) between them free. Thread structure (1) according to claim 1, wherein the volume of the thermoplastic matrix (6) is determined in such a way that the thermoplastic matrix (6) flows into the spaces (7, 8) together with individual threads (5) by a subsequent and predetermined pressing process and partially fills them or completely filled. Thread structure (1) according to claim 1 or 2, wherein the thread bundles (2,3,4); (2',3',4'); (2", 3", 4") are saturated with the thermoplastic matrix (6). Thread structure (1) according to one of the preceding claims, wherein the thread structure (1) is an open lattice structure. Thread structure (1) according to one of the preceding claims, wherein this is completely and uniformly impregnated with a form-fitting thermoplastic matrix (6) and the thread bundles (2,3,4); (2',3',4');(2",3",4") can no longer move relative to each other. Thread structure (1) according to one of the preceding claims, wherein the existing thermoplastic matrix (2,3,4); (2',3',4'); (2",3",4") connects the crossing thread bundles at the connection points. Thread structure (1) according to one of the preceding claims, wherein all thread bundles (2,3,4); (2',3',4'); (2", 3", 4") are provided with a thermoplastic matrix (6) in the manner of a composite material. Thread structure (1) according to any one of the preceding claims, wherein each thread bundle (2,3,4); (2',3',4'); (2",3",4") has individual threads laid in several layers. Thread structure (1) according to any one of the preceding claims, wherein the distance is more than 2 mm. A final prepreg product (14) comprising a thread structure (1) according to any one of the preceding claims, having holes defined by longitudinal and transverse dimensions located between the individual thread bundles (2, 3, 4); (2', 3', 4'); (2", 3", 4"). The final prepreg product (14) of claim 10, wherein the composite is uniformly interspersed with monofilaments (5) in each direction and interspersed with thermoplastic matrix throughout the longitudinal and transverse dimensions. Prepreg end product (14) according to Claim 10 or 11, in which the thread structure is pressed and the individual threads (5) are laid evenly. Prepreg end product (14) according to any one of claims 10 to 12, wherein this is a three-dimensionally shaped end product (14), in particular with evenly embedded individual threads (5) which come from the original thread bundles (2, 3, 4); (2', 3', 4');(2",3",4"). Component manufactured by injection molding or forming, in particular 3D forming, from a prepreg end product (14) according to one of Claims 10 to 13.

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