DE4015502A1 - TEXTILE REINFORCEMENT INSERT AND FIBER REINFORCED COMPOSITE - Google Patents

Description

The present invention relates to a textile reinforcement insert which consists of a nonwoven made of synthetic fibers or such contains, at least some of the synthetic fibers being hollow fibers, and a fiber-reinforced composite material containing them.

Fiber-reinforced composite materials in the sense of the present invention consist of a polymer matrix of a thermoplastic or preferably a resin curable by crosslinking, into which a fiber mass is embedded.

DE-A-30 22 255 describes a fiber-reinforced composite material and a fiber mat used for its manufacture is known.

This mat is made from uneven threads that pass through Spinning fiber flake, in particular made from reject flake becomes. It also contains hair, cavities, swellings and discontinuities the surface, which is a good anchorage of the fiber mat with the Should cause matrix resin.

Mainly polyester, epoxy, phenol, Use of silicone, polyethylene and cellulose resins as well as elastomers. Because of the inhomogeneity, the material and the structure of the here This known composite material is sufficient for the spun fiber mat used only moderate quality requirements.

DE-B-12 14 193 describes an anisotropic composite material a variety of superficially united and essentially parallel mutually arranged, hollow filaments, embedded in a matrix resin are.

From DE-C-30 13 134 a method is known for the production of Molded parts by deep drawing and / or pressing thermoplastic Fiber-containing fiber mats, in which the deformation in the thermal softened condition of the fibers is running. Essential to this  The method is that a tangled fiber fleece is used as the mat, the hollow Contains staple and continuous fibers that are gas-tight at suitable intervals Have locking points. Between the closure points of the fibers forms a kind of incompressible, elongated air cushion that the Fibers stabilized so that in the thermoplastic softened state almost unlimited deformability of the mat is achieved. A composite material is not described in this document.

Fibers are to a far greater extent than non-extruded polymer masses suitable to absorb high tensile loads and therefore it has been around for a long time known plastic components that absorb high mechanical loads are to be reinforced by fiber inlays.

High demands are placed on such fiber inserts with regard to mechanical strength, dimensional accuracy, absorbency, d. H. Capillary activity, Matrix compatibility and matrix adhesion, elasticity and reference elongation posed. This combination of advantageous properties must Deposits not only exist in the raw state, but also after Influence of the matrix material and the embedding and hardening conditions remain.

In particular, the need for high tensile strength, one of which Matrix material adjusted as possible elasticity module and in the Most cases have the required optimal isotropy of these properties resulted in synthetic fiber nonwovens as textile reinforcing inserts be used.

Synthetic fibers are suitable for the production of textile reinforcement inserts for composite materials in particular because they are mechanical Properties are adapted very precisely to the matrix properties can, because of the inherent high strengths and their high Long-term stability. Suitable matrix-reinforcing textile fabrics are suitable especially nonwovens, d. H. consolidated nonwovens because they are special on the one hand are inexpensive to manufacture, on the other hand because of the confusion of Filaments also have almost unsurpassed isotropic advantages have their mechanical properties. Nonwovens can, however  also with a targeted anisotropy of their mechanical properties generate by providing fiber fractions therein that are in certain Preferred directions run.

Composites have been around for a long time and to an increasing extent for the construction of larger moldings such. B. boat hulls or vehicle bodies used. With this use there is a constant Efforts to save material and weight, however, the mechanical The strength of the components must not be reduced.

Because of these demands from users, it is becoming increasingly difficult Fiber reinforcements with the combinations of properties described above to provide at a reasonable cost.

Often, the combination of properties that is required in individual cases and especially highest mechanical strength only with relatively thick and thus heavy and expensive nonwovens can be achieved.

Attempts to provide the lightest possible fiber inlays, the increased The requirements of the users are already different Directions have been taken.

Surprisingly, it has now been found that high requirements can be achieved to the reinforcement material with nonwovens much lower Basis weight and thus with much less material satisfy if the fiber material of the nonwoven contains hollow fibers. Another advantage of the reinforcing material according to the invention is in that in many cases there is a significant saving in matrix material allowed, which also benefits the weight and cost reduction is coming.

The present invention thus relates to a textile reinforcement material, which consists of a nonwoven made of synthetic fibers or contains one, at least some of the synthetic fibers being hollow fibers are.  

The proportion of hollow fibers in the nonwoven that gives it the desired combination of properties mediates, may be surprisingly small. There is often a noticeable economic and technical advantage even with a textile reinforcement insert, the nonwoven of which is at least Contains 10% hollow fibers.

As a rule, it is advisable to use a textile reinforcement insert whose nonwoven contains 50-100% hollow fibers, the highest technical requirement profiles are naturally fulfilled with nonwovens can, which consist of 100% hollow fibers.

The titer of the synthetic fibers in the textile according to the invention Reinforcing insert contained nonwoven are in the for textile Reinforcement inserts usual area.

They are usually between 0.5 and 50 dtex, preferably in Range from 2 to 20 dtex.

From case to case, it may be appropriate to use mixed titers, in particular With such nonwovens for textile reinforcement inserts, that are not 100% hollow fibers, hollow fibers and full fibers have different titers.

The synthetic fibers can advantageously be continuous fibers or staple fibers with stack lengths of 2-20 cm.

However, it is also readily possible to use nonwovens that contain both continuous and staple fibers.

So z. B. in many cases the desired combination of properties of a filament nonwoven (such consists of continuous filaments) Set a suitable proportion of hollow staple fibers. Mixtures of hollow and non-hollow can of course also be used Staple fibers are laid down to form a staple fiber fleece.

The in the nonwovens of the textile reinforcement inserts according to the invention Synthetic fibers contained can contain one or more cavities have, and the cavities can in the direction of the fiber axis be short to very short or extend the entire length of the fiber. Accordingly, hollow fibers in the sense of this invention are both foam fibers  as well as hollow fibers with one or more over larger fiber sections or cavities extending over the entire length of the fiber. The void fraction of the synthetic fibers is essential. Particularly suitable for the textile reinforcement inserts according to the invention are synthetic fibers, the void fraction 3-40 vol .-%, preferably 5-20% by volume.

The suitable synthetic fibers generally consist of spinnable Polyamide, polyethylene, polypropylene or polyester.

Synthetic fibers made from polyester, in particular from polyethylene terephthalate, are preferred.

The consolidation of the nonwovens of the textile reinforcement insert according to the invention can in principle be done in any known manner. That's the way it is for example possible to solidify the fleece with a binder which the fleece is impregnated and which is then cured or the binder can be a melt binder, e.g. B. in powder form or is incorporated into the fleece in the form of binder threads, and the fleece solidified under the influence of heat to form the nonwoven.

The nonwoven can also be consolidated to form a nonwoven by calendering take place, partly mechanical felting of the filaments, partly an autogenous weld occurs at the crossing points.

Textile reinforcement inserts according to the invention have proven to be particularly advantageous proven that consist of a nonwoven or a contain those that have been mechanically consolidated. Under one mechanical consolidation is to be understood as needling or also z. B. hydromechanical solidification, as z. B. in the EP-A-01 08 621 is described.

The weight per unit area of the textile reinforcement insert according to the invention depends of course on the intended use. Usually it is included 50 to 500 g / m², preferably 100 to 300 g / m².

Another preferred embodiment of the textile according to the invention Reinforcing insert has a spunbond, in particular, as the nonwoven fabric bung bond solidified by needles.  

Such embodiments of the textile are also particularly preferred Reinforcement insert in which several of the above preferred Features are combined.

The present invention also relates to a method for producing the textile reinforcement insert according to the invention by placing synthetic continuous or staple fibers in themselves known way on a moving surface, subsequent solidification and, if necessary, combination with another textile material is characterized in that at least part of the deposited synthetic fibers Are hollow fibers.

In the production of spunbond nonwovens, the invention one Containing proportion of hollow fibers can be a mixture of hollow and non-hollow staple fibers in the desired mixing ratio in itself known dry or by a wet-laid process to the nonwoven stored and then solidified.

But it is also possible to make nonwovens from endless fibers and staple fibers to generate by placing a in the filing of the continuous fibers Provides admixture of the staple fibers. In this case you can choose the continuous fibers or the staple fibers made wholly or partly of hollow fibers consist.

Also in the manufacture of the nonwovens using the spunbond process it is possible to mix solid fibers and hollow fibers during storage. For this For example, the hollow fibers can be produced separately and from fiber reservoirs, e.g. B. bobbins, deducted and by blowing nozzles fed into the fiber stream of the full fibers directed towards the storage be, or the spinning beams that are used to produce the nonwoven filaments can serve, in addition to spinning openings for full fibers, spinning openings for hollow fibers, the ratio of the different spinning orifices and the amount of filaments spun from it desired ratio of solid and hollow fibers in the invention corresponds to textile reinforcement insert.

As a rule, reinforcement inserts according to the invention are used for the production deposited at least 10% hollow fibers.  

The proportion of deposited hollow fibers is preferably 50- 100%, and to achieve the maximum effects are 100%, the deposited Fibers Hollow fibers.

The nonwoven is consolidated to form the nonwoven in a manner known per se Way using a binder, or a melt binder or by calendering or, preferably, by needling.

Binder can e.g. B. polymer solutions or dispersions or latices be applied to the fleece by impregnation or spraying and after the evaporation of the liquid phase to the Form crossing points of the filaments "tie sail".

However, thermoset binders can also be used, if necessary with a heat treatment, harden and fix the fiber crossing points. Also melt binders, the z. B. in the form of powders or preferably be incorporated into the fleece in the form of binder fibers, and which in Heating the fleece above its melting point at the fiber crossing points converge and form binding points that after the Re-cooling the nonwoven to solidify the nonwoven can do with good Success.

A similar hardening can be done by "autogenous" welding of the fleece filaments at their crossing points if you do that Nonwoven calendering near the melting temperature of the nonwoven filaments submits.

Mechanical solidification is preferred. No chemical occurs here or thermal load on the filament material, so that the advantageous physical properties due to the filaments their manufacture, e.g. B. by rapid spinning and stretching operations are conveyed, undiminished transferred to the nonwoven.

The textile reinforcement inserts according to the invention can either consist only of a nonwoven fabric of the type described above or them can in addition to the nonwoven fabric other textile materials such. B.  Fabric or an additional textile layer (e.g. a decorative layer or a Placed filaments to achieve special strength in one certain direction) included. With these additional layers the nonwoven combines into a textile composite material that additional Can solve tasks.

The present invention also relates to fiber reinforced composites from a polymer matrix into which a reinforcing insert according to the invention of the type described above is embedded. Suitable as a polymer matrix basically all for the manufacture of fiber reinforced composites known, in particular crosslinkable polymer compositions, such as e.g. B. polyester, epoxy, phenolic or silicone resins.

Crosslinkable polyester and epoxy resins are particularly suitable by a suitable crosslinker or by exposure to heat or e.g. B. can be crosslinked by ionizing radiation.

The composite materials according to the invention are produced in known manner by soaking or coating, in particular double-sided coating of the reinforcing insert according to the invention the uncrosslinked matrix polymer, possibly shaping the soaked reinforcement insert by a common method, e.g. B. by pressing, pulling or placing on a mold and then curing with crosslinking of the polymer material.

Claims (16)

1. Textile reinforcement insert consisting of or containing a nonwoven fabric made of synthetic fibers, characterized in that at least some of the synthetic fibers are hollow fibers. 2. Textile reinforcement insert according to claim 1, characterized in that at least 10% of the synthetic fibers are hollow fibers. 3. Textile reinforcement insert according to at least one of claims 1 and 2, characterized in that 50-100%, preferably 100%, of the synthetic fibers are hollow fibers. 4. Textile reinforcement insert according to at least one of claims 1 to 3, characterized in that the cavities of the hollow fibers extend over the entire length of the fiber. 5. Textile reinforcement insert according to at least one of claims 1 to 4, characterized in that the void fraction of the synthetic fibers 3-40 vol .-%, preferably 5-20 vol .-%, is. 6. Textile reinforcement insert according to at least one of claims 1 to 5, characterized in that the synthetic fibers made of polyester, preferably made of polyethylene terephthalate. 7. Textile reinforcement insert according to at least one of claims 1 to 6, characterized in that the nonwoven fabric by a binder is solidified. 8. Textile reinforcement insert according to at least one of claims 1 to 6, characterized in that the nonwoven mechanically solidifies is.   9. Textile reinforcement insert according to at least one of claims 1 to 8, characterized in that the nonwoven is a filament nonwoven. 10. Process for the production of a textile reinforcement insert Claim 1, by filing synthetic continuous and / or staple fibers in a manner known per se on a moving surface Fleece, subsequent consolidation and, if necessary, combination of the nonwoven with a further textile material, characterized in that at least one Part of the deposited synthetic fibers are hollow fibers. 11. The method according to claim 10, characterized in that at least 10% of the deposited synthetic fibers are hollow fibers. 12. The method according to at least one of claims 10 and 11 thereby characterized in that 50-100%, preferably 100%, of the deposited Fibers are hollow fibers. 13. The method according to at least one of claims 10 to 12, characterized characterized in that the consolidation of the fleece to the nonwoven fabric using a binder or preferably mechanically. 14. Fiber-reinforced composite material made of a polymer matrix into which one Reinforcing insert is embedded, characterized in that it is a Reinforcing insert of claim 1 contains. 15. A fiber-reinforced composite material according to claim 14, characterized characterized in that it is a polymer or polyester or epoxy resin contains.   16. A method for producing the composite material of claim 14 by impregnation or coating, in particular coating on both sides a textile reinforcement insert with the uncrosslinked matrix polymer, if necessary, shaping the soaked reinforcing insert by a conventional one Process and subsequent curing with crosslinking of the polymer material, characterized in that a textile reinforcement insert of claim 1 is used.