AT525587A1 - Method for producing a fiber laminate, a fiber laminate and a use of a fiber laminate - Google Patents

Abstract

A method for producing a fiber laminate (1), wherein - a matrix (2) in the liquid state and fibers (3) are provided, - the fibers (3) are embedded in the matrix (2), while the matrix (2) in is in the liquid state, - during a curing process, waiting is made until the matrix (2) reaches a gel point, from which point the matrix (2) has essentially changed from the liquid to a plastic state, - a surface structure in the plastic state of the matrix (2). (10) is pressed onto the matrix (2) together with the fibers (3) embedded therein and - the curing process is terminated, whereby the fiber laminate (1) containing the matrix (2) and the fibers (3) embedded therein is obtained, the has the embossed surface structure (10).

Description

The present invention relates to a method for producing a fiber laminate, a fiber laminate and a use of a fiber laminate in the manufacture of gliding devices, in particular skis or snowboards, and/or in the manufacture of wind blades.

The production of fiber laminates, for example in the pultrusion process, is of course known per se. Fibers are embedded in a matrix while

the matrix is in the liquid state.

Fiber laminates are used, for example, in the manufacture of skis. The fiber laminates must have a surface structure, otherwise air pockets can form during the pressing process used to manufacture the skis. A surface structure prevents this because the surface structure creates a certain spacing of layers located above or below the fiber laminate almost until the end of the pressing process. through the arising

The air can then escape in the gaps.

Another positive effect of the surface structure is improved adhesion

between the layers.

In the prior art, the mentioned surface structure of the fiber laminate is produced by grinding the surface of the previously produced fiber laminate, which entails disadvantages. First of all, the grinding of fiber laminate is fundamentally undesirable because the grinding of the fibers can produce dust (for example glass fiber dust), the disposal of which is complex and difficult due to the particle size. If handled improperly, the grinding dust would also cause a considerable damage

represent environmental pollution.

Furthermore, grinding the prefabricated fiber laminate is undesirable because it uses more material than is actually necessary. Also in this regard, the grinding of the fiber laminate with regard to the

Material utilization and environmental compatibility disadvantageous.

Since the fibers in the laminate are not ideally evenly distributed and are sometimes even arranged on top of each other, the fibers are sanded to different degrees when sanding, which results in inhomogeneous mechanical

Set the material properties of the laminate.

Microfractures also occur in the laminate as a result of the sanding, which occur in the finished

product to predetermined breaking points.

The object of the invention is therefore to provide a method for producing fiber laminates and a fiber laminate with a surface structure, in which material can be saved and/or less harmful by-products, such as grinding dust,

accrue and/or more homogeneous material properties can be achieved.

With regard to the manufacturing process, this object is achieved by the features of claim 1, namely by

- a matrix in liquid state and fibers are provided,

- the fibers are embedded in the matrix while the matrix is in the liquid state,

- waiting during a curing process until the matrix reaches a gel point, after which the matrix has essentially changed from a liquid to a plastic state,

- in the plastic state of the matrix, a surface structure is embossed on the matrix together with the fibers embedded therein and

- The curing process is terminated, whereby the fiber laminate containing the matrix and the fibers embedded therein is obtained

has an embossed surface structure.

With regard to the fiber laminate, the object is achieved by the features of claim 9, namely by the surface of the fiber laminate an embossed

Has surface structure.

The embossing of a surface structure on a fiber laminate is not possible at any time. If the surface structure becomes too early during the

Curing process changes, the surface structure does not remain, because the

liquid matrix simply returns to its original state. Nor can the surface structure be embossed after the curing process

has ended because the matrix is no longer plastically deformable at this point in time.

According to the invention, the embossing of a surface structure onto a fiber laminate takes place after the gel point has been reached, but before the curing process has ended. A basic aspect of the invention is therefore that it is possible to impress a surface structure on the matrix together with the fibers embedded therein if one waits for the relatively short period of time in which the matrix is in a plastic state

(from the gel point) and the curing process has not yet ended.

According to the invention, post-processing, such as grinding, can be completely dispensed with, as a result of which material can be saved and undesired by-products, such as grinding dust, can be completely avoided. The fiber laminates according to the invention can therefore be used directly for further production,

be used for example by gliding devices or wind blades.

On the one hand, the elimination of grinding improves the working conditions in the vicinity of the plant for manufacturing the fiber laminates. In addition, as mentioned, no precautions have to be taken to dispose of the grinding dust.

Worn sanding belts also do not have to be changed.

Because the laminates do not have to be sanded at all, the material properties are more homogeneous, in particular mechanical properties such as elasticity, fracture toughness and resistance to delamination. In specific tests by the applicant, the mechanical tolerances of a fiber laminate according to the invention increased by 15%

8% reduced.

Another effect of the invention is that the surface structure is almost free

can be selected and thus adapted to the desired application.

According to the invention, a surface structure is understood to mean a structure which has elevations and/or depressions, ie is not smooth, and at least up to

corresponds to a certain extent to the embossing structure of an embossing tool.

In particularly preferred embodiments of the invention, the embedding

Fibers in the liquid matrix happen through a pultrusion process.

Embedding the fibers in the liquid matrix can also be referred to as impregnation

become. The liquid matrix preferentially wets all of the fibers.

In particularly preferred embodiments, the fibers are embedded in the matrix in a substantially unidirectional manner, resulting in a fiber laminate with fibers aligned in a substantially unidirectional manner. Embodiments with no

unidirectional orientation of the fibers are of course conceivable in principle.

Protection is also sought for the use of a fiber laminate in the manufacture of gliding devices, particularly skis or snowboards, and/or in the manufacture of wind blades. Wind blades can be the blades of a wind turbine

be understood.

Advantageous embodiments of the invention are in the dependent claims

Are defined.

A reactive and/or duroplastic matrix system can be used as the matrix

become.

That is, the matrix can be a resin or a reactive polymer precursor which, after impregnation of the fibers - e.g.

assisted by the influence of pressure and/or temperature — hardens.

Specifically, the matrix can be at least one of the following: e unsaturated polyester resins e vinyl ester resins

e diallyl phthalate resins

e methyl methacrylate resins

e epoxy resins

e polyurethanes

e phenol-formaldehyde resins

e amino resins

e Thermoplastic resin systems

e Biopolymers

As mentioned, the fibers can enter the matrix essentially unidirectionally

be embedded.

The fibers (also referred to as filaments) can be provided in bundle form (rovings). The bundles can thereby consist of essentially parallel!| aligned fibers or twisted or braided fibers

consist. Mixed forms are of course also conceivable in principle.

Examples of fibers that can be used with the present invention are at least one of the following:

- Glass fibers (Glass fibers are the most commonly used fiber types mainly because of their relatively low price. There are glass fiber types for different applications.)

- Carbon fibers (also: carbon fibers; These have high strength and low weight at the same time. Disadvantages can be brittle fracture behavior and low elongation at break.)

- Basalt fibers (basalt fibers are mineral fibers that are mainly used in container and vehicle construction because of their good chemical resistance and temperature resistance.)

- Ceramic fibers (endless ceramic fibers made of aluminum oxide, mullite (mixed oxide of aluminum oxide and silicon dioxide), SIBCN, SICN, SiC, etc. are expensive special fibers for high-temperature-resistant composite materials with a ceramic matrix. The non-oxide fibers, similar to carbon fibers, are obtained from organic resins, in those next to

carbon also contains silicon.)

- Aramid fibers (Aramid is the abbreviation for aromatic polyamide. The manufacturing process is very expensive and the price of aramid fibers is therefore comparable to that of carbon fibres. The essential properties are their low density and good damping properties.)

- Steel fibers (Steel fibers are mainly used in construction for steel fiber reinforced concrete. This application is growing rapidly and has particular economic advantages.)

- Natural fibers (The fibers most commonly used for the production of fiber composite materials are domestic wood fibers, flax and hemp fibers as well as subtropical and tropical fibers such as jute, kenaf, ramie or sisal fibers.)

- Nylon fibers (fibers with a high breaking elongation are advantageous if

the fiber laminate has to absorb disturbances.)

It can be provided that the fibers are washed through a bath with the matrix in the liquid

State drawn and thus embedded in the matrix.

The matrix together with the fibers embedded therein can be guided through a nozzle in order to at least change a geometric shape, in particular a thickness, of the fiber laminate

partially set.

The fact that the nozzle at least partially defines the geometric shape can be understood to mean that, for example, a thickness of the fiber laminate is defined by the nozzle to a certain degree of accuracy. Subsequent processes (e.g. shrinkage during the curing process, embossing of the surface structure) can further change the geometry of the fiber laminate. By guiding the matrix together with the fibers embedded in it through a pair of rollers (before or after embossing the surface structure), the thickness

ultimately be determined, but this is not mandatory. Alternatively, the nozzle can also change the geometry of the fiber laminate only in certain areas

set so that the nozzle the geometric shape of the fiber laminate in this way

only partially determined.

In order to trigger and/or accelerate the curing process, the matrix together with the fibers embedded therein can be heated, preferably by means of at least one

hotplate.

In particularly preferred exemplary embodiments, two heating plates can be provided, between which the matrix and the fibers embedded therein pass

becomes.

In particularly preferred embodiments, the at least one heating plate is in contact with the matrix and/or the fibers embedded therein in order to

improve heat transfer.

Provision can also be made for the at least one heating plate to apply a defined pressure and/or a defined force to the matrix including the matrix therein

embedded fibers exercises.

Heating plates can be powered directly with electrical energy or by means of a heating medium

(e.g. water or oil) are heated.

In principle, instead of heating plates, other devices, such as

Radiant heaters are used.

The temperature and/or the applied force and/or the applied pressure can

be controlled or regulated.

As already mentioned, it can be provided that the matrix together with the fibers embedded therein—preferably before the surface structure is imprinted—is guided through at least one pair of rollers in order to determine the thickness of the resulting fiber laminate. Embodiments, wherein the pair of rollers for adjusting the thickness are arranged in front of the at least one embossing roller in a feed direction

are also conceivable in principle.

The pair of rollers can be arranged opposite one another, so that the matrix, together with the fibers embedded in it, is in contact with both rollers at the same time

pair of rollers.

The rollers of the pair of rollers can preferably have an essentially smooth surface in order not to disturb the embossed surface structure. The rollers of the roller pair can accordingly also be referred to as "smoothing rollers".

become.

Provision can be made for the rollers in the pair of rollers to have a defined, controlled and/or regulated distance from one another in order to reduce the thickness of the

Adjust fiber laminate.

The surface structure can be embossed onto the matrix together with the fibers embedded therein by means of at least one embossing roller. For this purpose, the embossing roller has a negative structure, which after embossing appears as the surface structure of the

Fiber laminate shows.

The negative structure has indentations and/or elevations which, upon contact with the at least one embossing roller in the matrix together with the fibers embedded therein, have corresponding elevations and/or indentations and thus the

create surface structure.

Two embossing rollers can be used, which are arranged opposite one another so that the matrix and the fibers embedded in it are in contact with the matrix at the same time

the embossing rollers.

In principle, more than two embossing rollers could be used

for example, are partially arranged sequentially. Not all of the embossing rollers have to have the negative structure mentioned.

However, at least one of the embossing rollers must have a negative structure, so that

the surface structure can be embossed.

If two or more embossing rollers are used, the surface structure of the matrix, including the fibers embedded in it, can be embossed on two sides. According to the invention, therefore, a fiber laminate can be provided which

Has surface structure on one or two sides.

As an alternative to embossing rollers, belts could in principle also be used,

which have the mentioned negative structure.

The fact that embossing rollers or smoothing rollers are in contact with the matrix and the fibers embedded in it at the same time can be understood to mean that these rollers are arranged at the same point in relation to a feed direction of the matrix and the fibers embedded in it, so that they are in contact with the same area of the matrix including the fibers embedded in it (ie

"simultaneously" in relation to a feed position).

In order to reach the gel point without the curing process of the matrix being terminated before the surface structure is imprinted, defined temperature ranges and/or distances between a point at which the curing time begins and

a point where the surface structure is imprinted.

In tests by the applicant in the form of a pultrusion process, target temperatures of less than 400° C (especially with radiant heaters), less than 200° C (especially with electrically heated heating plates) and/or less than 100° C (especially with heating plates heated by a heating medium) as advantageous

exposed.

Furthermore, with a movement speed of the matrix including the fibers embedded in it during pultrusion of less than 12 m per minute, the following distance ranges have emerged at which the curing process can be ended (according to the invention, the surface structure is imprinted before the curing time):

- after a nozzle: 7 m to 12 m

- after entering a heating zone: 5.5 m to 10.5 m

Further advantages and details of the invention are based on the figures and the

associated figure description visible. show:

Fig. 1 is a schematic diagram of an embodiment of a

manufacturing process according to the invention,

2a and 2b photographic representations of two exemplary embodiments of an embossing roller, FIG. 3 a photographic representation of a laminate according to the invention,

4a and 4b two diagrams of the method according to the prior art and

5 is a diagram showing the gel point.

Fig. 1 shows a schematic diagram of an embodiment of the

Manufacturing process according to the invention.

From a supply 8 of fibers 3 in bundle form (rovings), the fibers 3 are guided via a roving creel 9 and rollers through a bath 4 in which the matrix 2 is present in liquid form. Thereby the fibers 3 are embedded in the matrix 2, i.e. with the

Matrix 2 impregnated.

In this exemplary embodiment, the matrix 2 is an epoxy based on bisphenol A

Resin with an isophorone diamine hardener.

The fibers 3 are guided in a direction parallel to one another through the bath 4, so that ultimately a unidirectional alignment of the fibers 3 in the

Fiber laminate 1 results.

After impregnation in the bath 4, the matrix 2, together with the fibers 3 embedded therein, is guided through a nozzle 5, which has the geometry of the fiber laminate 1 roughly

determines. The geometry of the fiber laminate 1 can be seen in FIG.

For feeding (actually: pulling through) the fibers 3 through the roving creel 9, the

Bad 4, the nozzle 5 and the following elements, a trigger 12 is provided. The

Trigger 12 includes two chain bands, which the matrix 2 and the therein

embedded fibers 3 pulls through the elements mentioned.

In this respect, the present production process is a known pultrusion process, with which fiber laminates are produced in endless production

can become.

After the nozzle 5 the matrix 2 together with the fibers 3 embedded therein is moved through a heating zone 11 . The heating zone 11 contains heating plates 14 which heat the matrix 2 . The curing process of the matrix 2 is initiated by the heating

set and/or accelerated.

The length of the heating zone and the pull-through speed are selected in such a way that the matrix 2 reaches the gel point at the end of the heating zone and after being guided through a pair of rollers 7, at which the matrix 2 is in a plastic state (hardening

through the formation of long-chain molecules).

At this point, embossing rollers 6 are provided, the surface structure 10 on the matrix 2 including the through depressions and elevations (negative structure).

fibers 3 present therein.

In this exemplary embodiment, only the upper embossing roller 6 in FIG. 1 is provided with the negative structure. The lower embossing roller is therefore in this

Embodiment smooth.

After the surface structure 10 has been embossed according to the invention, the curing process of the matrix 2 continues until it is completely cured, so that the matrix 2 changes from the aforementioned plastic state to a completely hardened state. In this completely hardened state, it would no longer be possible to emboss a structure, since the matrix 2 would only deform slightly elastically

or would break multiple times under the influence of the embossing.

In the present exemplary embodiment, there is a pair of rollers 7 in front of the embossing rollers 6

provided, by means of which the thickness of the fiber laminate 1 can be adjusted.

At the location of the pair of rollers 7, the matrix 2 is still in the plastic state

Condition.

The embossing rollers 6 and the pair of rollers 7 are spatially arranged close to one another

and therefore form a smoothing and embossing unit.

After stripping 12, the fiber laminate can be trimmed as desired.

As mentioned, Fig. 2a and Fig. 2b show two exemplary embodiments for embossing rollers 6,

where different negative structures are visible.

FIG. 3 shows fiber laminates 1 according to that described in connection with FIG

Manufacturing processes were provided with a surface structure 10.

The exemplary fiber laminates 1 shown in FIG

several layers of fiber bundles on top of each other.

For comparison, a production method according to the prior art was illustrated in FIG. 4a and in FIG. 4b. It can be seen that the fiber bundles (rovings) are not ideally level in the laminate 21 . The subsequent grinding process using a grinding belt 22 produces a surface with a certain structure. However, the individual fibers are sanded down to different depths or even sanded away completely. It is obvious that this not only creates harmful sanding dust, but also that the material properties, depending on the

local position of the fibers in the laminate 21, turn out differently.

In contrast, with the invention, a fiber laminate 1 can be produced without wasting material, which is also far more homogeneous

Has material properties and a freely selectable surface structure.

5 shows an exemplary diagram for clarifying the gel point. On the one hand, the temperature curve (solid line) of a volume element of the matrix 2 during the pultrusion and on the other hand, are plotted

Viscosity (dotted) of the same, each against time.

After an initial drop in viscosity due to the increasing temperature in the heating zone 11 and a subsequent flat course of the viscosity, during which the curing reaction of the matrix 2 begins, the viscosity increases relatively steeply. the latter

is the result of the hardening reaction, which creates 2 long-chain molecules in the matrix

are formed.

During this period, the gel point (vertical line) falls. It marks the time from which the matrix 2 is plastically deformable. The strong increase in viscosity that continues after the gel point ultimately leads to a hardened state in which

which the matrix 2 is no longer plastically deformable. It can be seen that due to the strong increase in viscosity, only a relatively short time window is available in which the matrix 2 can be plastically deformed. A

Basic aspect of the invention is to exploit this short time window to the

Imprint surface structure 10 under plastic deformation of the matrix 2.

Innsbruck, October 19, 2021

Claims (19)

patent claims Claims 1. A method for producing a fiber laminate (1), wherein - a matrix (2) in the liquid state and fibers (3) are provided, - the fibers (3) are embedded in the matrix (2) while the matrix (2) is in the liquid state, - one waits during a curing process until the matrix (2) reaches a gel point, after which the matrix (2) has essentially changed from the liquid to a plastic state, - In the plastic state of the matrix (2), a surface structure (10) is embossed onto the matrix (2) together with the fibers (3) embedded therein and - The curing process is terminated, whereby the matrix (2) and the fibers (3) embedded therein containing fiber laminate (1) is obtained, the has embossed surface structure (10). 2. The method of claim 1, wherein the matrix (2) is a reactive and / or thermosetting matrix system is used. 3. The method according to any one of the preceding claims, wherein the fibers (3) in Essentially unidirectionally embedded in the matrix (2). 4. The method according to any one of the preceding claims, wherein the fibers (3) are drawn through a bath (4) with the matrix (2) in the liquid state and thereby in embedded in the matrix (2). 5. The method according to any one of the preceding claims, wherein the matrix (2) together with the fibers (3) embedded therein through a nozzle (5) is guided to a geometric shape, in particular a thickness, of the fiber laminate (1) at least partially set. 6. The method according to any one of the preceding claims, wherein the matrix (2) together the fibers (3) embedded therein, preferably by means of at least one 2 91304 324l Hot plate (14) is heated to trigger the curing process and / or accelerate. Method according to one of the preceding claims, wherein the matrix (2) together with the fibers (3) embedded therein - preferably before the imprinting of the surface structure (10) - is guided through at least one pair of rollers (7) in order to set a thickness of the resulting fiber laminate (1). Method according to one of the preceding claims, in which the surface structure (10) is applied to the matrix (2) by means of at least one embossing roller (6). together with the fibers (3) embedded therein. Fiber laminate, produced in particular according to one of Claims 1 to 8, with fibers (3) embedded in a matrix (2), characterized in that a surface of the fiber laminate (1) has an embossed surface structure (10). Use of a fiber laminate (1) according to claim 9 and/or produced according to one of claims 1 to 8 in the manufacture of gliding devices, in particular skis or snowboards, and/or for the manufacture of wind blades. Innsbruck, am October 19, 2021