EP1499763B1 - Glass fiber roving - Google Patents

Abstract

A strand based on glass fibers with a tau/mu<SUP>2 </SUP>ratio greater than 9, where tau is the yardage of the strand in tex and mu is the filament diameter in mum. The strand has at least 6000 filaments with a yardage greater than 1200 tex and a filament diameter greater than 11 mum.

Description

The invention relates to a wick consisting of a plurality of filaments based on glass fibers. The wick may be in the form of a coil called roving or roving.

1. A - Le tissage et autres procédés utilisant des machines textiles, conduisant à des renforts plans tissés ou non.
   Les tissus et autres renforts lourds à base de rovings (environ ou plus de 1000g/m²) sont surtout utilisés pour la fabrication de pièces en matériau composite pouvant être très sollicitées mécaniquement. Ils trouvent une application dans des pièces utilisées de manière statique, telles que des panneaux de caissons isothermes pour camions frigorifiques, ou bien dans des pièces utilisées de manière dynamique telles que des pales d'éoliennes qui subissent de fortes oscillations vibratoires.
2. B - La pultrusion consistant à imprégner de résine un renfort de fils continus puis à le former par traction au travers d'un moule (filière) chauffé qui polymérise la structure profilée ainsi réalisée. Ce procédé permet de fabriquer des produits de renfort oblongs, tels que des joncs ou des éléments pour réaliser des caillebotis.
3. C - L'extrusion thermoplastique qui consiste à fabriquer des granulés de matière thermoplastique renfermant des fibres dites longues, les fibres continues étant introduites dans une extrudeuse et enrobées par la matière plastique en sortie d'extrudeuse pour être découpées en granulés. Ce procédé permet d'obtenir des pièces renforcées pour la construction automobile.
4. D - L'enroulement filamentaire consistant à enrouler sous tension constante un renfort de fibres continues imprégné de résine sur un mandrin tournant de forme appropriée pour obtenir après polymérisation un corps de révolution creux tel qu'un tuyau.

Rovings have various destinations. As for composite materials, rovings are the reinforcement of plastics. The processes for implementing fiberglass rovings are very varied. These methods include:

1. A - Weaving and other processes using textile machines, leading to planar reinforcements woven or not.
   The fabrics and other heavy reinforcements based on rovings (approximately or more than 1000g / m ² ) are mainly used for the manufacture of composite material parts that can be highly mechanically stressed. They find application in statically used parts, such as isothermal box panels for refrigerated trucks, or in dynamically used parts such as wind turbine blades that undergo strong vibrational oscillations.
2. B - The pultrusion consisting of impregnating a reinforcement of continuous threads with resin and then forming it by pulling through a heated mold (die) which polymerizes the profiled structure thus produced. This method makes it possible to manufacture oblong reinforcing products, such as rods or elements for making gratings.
3. C. Thermoplastic extrusion, which consists of producing granules of thermoplastic material containing so-called long fibers, the continuous fibers being introduced into an extruder and coated with the plastic material at the extruder outlet to be cut into granules. This process makes it possible to obtain reinforced parts for the automobile industry.
4. D - The filament winding of winding under constant tension a reinforcement of continuous fibers impregnated with resin on a rotating mandrel of suitable shape to obtain after polymerization a hollow body of revolution such as a pipe.

The invention more particularly relates to the locks for making reinforcements from rovings whose current title of the lock reaches 1200 tex or more with a filament diameter of 12 microns or more. We recall that the title of a thread or a wick is its linear density (1 tex = 1 g / km). The title of the wick varies proportionally to the square of the diameter of the filaments and proportionally to the number of filaments constituting it.

The title of a wick is a factor of its mechanical strength, while the diameter of the filaments affects the curability of the yarn or wick and therefore the flexibility of the fabric that can be obtained. The higher the titre, the stronger the yarn, and the higher the diameter of the filaments, the more difficult it will be to bend.

The rovings are obtained either directly from filaments from a die and gathered under it in a single wound bobbin (they are called direct rovings), or indirectly from son that are derived from primary coils called cakes and are assembled to constitute a final wick of desired title (we call them assembled rovings).

The maximum number of filaments constituting a wick of direct roving is limited by the number of holes of the die from which flow the glass nets forming after mechanical drawing said filaments. The number of filaments is strictly equal to the number of holes in the die. This number of holes today does not exceed about 4000 or even 4500, which makes it possible to obtain direct rovings, for example of 1200 tex / 12 μm , 2400 tex / 17 μm , or 4800 tex / 24 μm. or 9600 tex / 33 μ m.

It is conventional to express the filament diameter and the number of filaments as whole numbers. Indeed, for simplification of language, it states the number of die holes and the number of filaments of the wick according to a round number of hundreds (for example a wick of 4024 filaments will be said to 4000 filaments). The round number may differ from a few tens of the exact number.

As for the diameter of filaments, it is a nominal value, conventionally expressed by an integer number of micrometers. It differs in general from less than 0.5 μm from the average value of the diameter of all the filaments constituting the wick.

Also in the rest of the text, integers should be considered as rounded values.

For certain applications, we think for example of blades of wind turbines which undergo in time a phenomenon of fatigue due to quasi-continuous stresses generated by the wind, it would be desirable that the title of the lock currently of 2400 tex is even higher so as to simplify the manufacturing process blades, on the other hand allow to manufacture blades of very large dimensions (40 meters and more) which today however require a large number of layers of reinforcement.

The title of a roving wick can be increased by increasing the diameter of the filaments and / or their number.

The increase in diameter is the most obvious to achieve but is not always desirable for reasons of poorer curvature of the wick that causes weaving more difficult and leads to lower quality products. The weaving is frequently interrupted by filaments that break, the fabric is often defective considering the requirements of flatness and regularity of the dynamic applications in particular. In addition, the glass surface offered in contact with the impregnating resin is less, the glass-resin adhesion is therefore less good and the mechanical performance of the composite is lower. For these reasons, some professions have established standards that limit the permissible filament diameter to 17 μm .

In the case of pultrusion, the locks now have titles of up to 4800 tex, for example US 4,802,331; for reasons of productivity and dimensions of parts, it is also desired to increase the title, but the increase in the diameter of the filaments causes discomfort in the use of such locks, the filaments breaking and forming kinds of thorns which on the one hand sting and wound the operators and on the other hand dirty the resin that impregnates the reinforcement. For this reason, the transformers require in this case that the diameter of filaments does not exceed 24 μ m, some even requiring that this diameter does not exceed 19 μ m.

It is therefore preferred to increase the titre by increasing the number of filaments.

The increase in the number of filaments is achieved either by the combination of several wicks from a plurality of cakes, which does not simplify the manufacture and rather contributes to an increase in costs, either by the combination of several wicks of filaments from several dies and grouped on the same winder, which is not without generating a concern for performance because of the statistical rise in the number of breaks in the global wick by the dependence of a plurality of dies.

In addition, the inventors have demonstrated that the combination of a plurality of locks had disadvantages that could be prohibitive as to the quality of the solder coil and the manufactured product from the coil. So, for the combination of several strands of cakes, the coil obtained has loops on its edge which is not suitable in terms of quality of presentation for sale, and these loops may cause entanglement of the wick when unwinding at the weaving for example. With the combination of filaments from a plurality of dies, even if the coil obtained has no apparent defects, unwinding the strands of filaments tend to separate, one then will be pulled more than the other ( or others) during weaving, for example. This unevenness of tension will affect the flatness of the fabric that will be curled, the fabric will not be able to be properly impregnated with resin and will result in weakened mechanical properties for the composite material.

The object of the invention is therefore to provide a glass fiber wick which has a higher or identical title than those existing on the market without being accompanied by an increase in the diameter of the filaments, while maintaining a quality at least equivalent (especially during its implementation), and maintaining a simplicity in its manufacture.

qui est supérieur à 9, où τ est le titre de la mèche en tex et µ est le diamètre des filaments constituant la mèche en µm, et comporte au moins 6000 filaments, son titre étant supérieur à 1200 tex, et le diamètre de chaque filament étant supérieur à 11 µm, la mèche étant issue d'une unique filière.According to the invention, the wick is characterized by the ratio $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}$

which is greater than 9, where τ is the title of the wick in tex and μ is the diameter of the filaments constituting the wick in μm, and comprises at least 6,000 filaments, its titre being greater than 1200 tex, and the diameter of each filament being greater than 11 μm, the wick being from a single die.

Advantageously, the wick is in the form of a wound roving directly under the die.

For example, the wick comprises about 8000 filaments each about 17 microns in diameter and has a title of 4800 tex. This type of wick is particularly suitable for the manufacture of unidirectional or multiaxial reinforcements, used in particular for wind turbine blades. Indeed, the diameter of the filaments remains identical to that existing on the 17 μm market for wind turbine blades; weaving is thus not made more difficult. And the title is advantageously higher than the existing one, of 2400 tex for a diameter of 17 microns, leading to a heavier reinforcement.

In another example, the wick comprises about 8000 filaments each about 24 microns in diameter and has a title of 9600 tex. Such a wick is preferred for the production of profiled pieces of great length and reduced section by the pultrusion process.

As another example, the wick comprises about 8000 filaments each about 12 microns in diameter and has a titer of 2400 tex for the manufacture of rushes by the pultrusion-fine process.

Thus the wick of the invention can be used in the manufacture of composite materials via weaving processes, or pultrusion or extrusion or filament winding, and a particular application is for example that of wind turbine blades.

Finally, the wick may consist entirely of glass filaments or may be composed of, for example, glass and thermoplastic composite filaments.

Such locks are thus obtained by increasing the number of filaments drawn from the die, which makes it necessary to have dies with a greater number of holes than in the prior art.

Until now, coils with such a large number of filaments that can for example reach the number of 8000 as here in the invention and from a single sector did not exist on the market because the current glass fiberization installations are designed to accommodate bottoms of established sizes and with approximately 4500 orifices. To further increase the number of orifices, it would be necessary for the same die bottom surface to position the orifices even more tightly relative to each other, which would bring the filaments flowing between them. The risk would then be certain to see the filaments meet and stick together, thus preventing the fibering process.

However, until now, no consideration had been given to the possibility of making new dies, the bottom of which would be provided with a greater number of orifices, to double existing ones, by increasing the bottom area. die die pierced said holes while being able to integrate into an existing fiberization installation. Also, according to the invention, the device for manufacturing the wick of the invention comprises a die whose bottom consists of a plate provided with more than 4500 orifices, in particular 8000, and with a surface greater than that of an existing plate at present. provided with at most 4500 orifices.

• la figure 1 illustre schématiquement le dispositif de fabrication d'une mèche selon l'invention;
• la figure 2 illustre des courbes représentatives, selon le titre d'une mèche, du nombre de filaments de la mèche en fonction du diamètre des filaments.

Other advantages and characteristics of the invention will appear on reading the description which follows with reference to the appended drawings, in which:

• Figure 1 schematically illustrates the device for manufacturing a wick according to the invention;
• FIG. 2 illustrates representative curves, according to the title of a wick, of the number of filaments of the wick as a function of the diameter of the filaments.

The fiberglass wick 1 of the invention consists of more than 4000 filaments from a single die 13 as visible in Figure 1. The wick 1 is wound to form a direct roving R.

The composition of the glass is for example that of glass E.

The die 13 is provided at the bottom with a plate 14 which is provided with a multitude of orifices 15, such as pins, from which the molten glass flows to be stretched into a multiplicity of filaments 16. The number The number of orifices is greater than 4500, preferably greater than 6000, and can, for example, reach 8000, and even exceed that number of 8000.

The filaments are gathered in a single ply 17 which comes into contact with a coating device 20 for coating each filament with an aqueous or anhydrous size. The device 20 may consist of a tank continuously fed by a sizing bath and a rotating roller whose lower part is constantly immersed in the bath. This roll is permanently covered with a film of size which is taken in passing by the filaments 16 sliding on its surface.

The sheet 17 then converges to an assembly device 21 where the different filaments are joined to give birth to the wick 1. The assembly device 21 may be constituted by a simple grooved pulley or a plate provided with a notch .

The wick 1 leaving the assembly device 21 enters a wire guide 22 to be wound around a support 23 with a horizontal axis with respect to the vertical arrival of the wire to the guide wire. The wick is thus wound directly from the die to constitute the direct roving R. The stretching speed is typically between 10 and 60 meters per second.

The plate 14 of the die bottom is therefore designed with more than 4500 orifices, here 8000, to form 8000 filaments. The increase in the number of filaments thus provided compared with the number existing in the state of the art which does not exceed not 4500 has a real interest. For some applications, in view of a given constant titer, it is preferable to increase the number of filaments by decreasing their diameter rather than keeping the number of filaments with a larger diameter constant. Thus, a fabric to be impregnated with resin will exhibit better fatigue strength in its dynamic use when the contact surface of the resin with the glass filaments is larger. Now this intimacy of contact, for an identical size of a wick of 4800 tex, is increased with a constitution of 8000 filaments 17 μm in diameter instead of 4000 filaments of 24 μm diameter. The multiplier factor of contact intimacy is about 1.4 when one goes from 4000 to 8000 filaments.

Such a wick of 8000 filaments of 17 .mu.m diameter with a titer of 4800 tex will find particular application in the manufacture of unidirectional and multiaxial reinforcements for the reinforcement of wind turbine blades.

où f est le nombre de filaments, τ le titre, et µ le diamètre en µm, 490 étant un facteur multiplicateur intégrant la densité du verre.It is recalled that the number of filaments, the title of the wick and the diameter of the filaments are connected by the following formula: $$\frac{\mathrm{f}}{\mathrm{490}}\mathrm{=}\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}$$

where f is the number of filaments, τ the title, and μ the diameter in μm, 490 being a multiplying factor integrating the density of the glass.

qui est supérieur en valeur entière à 9. S'il n'est pas aisé de comptabiliser le nombre de filaments d'une mèche une fois le produit sur le marché, en revanche il est plus facile de calculer le rapport $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}$

après avoir mesuré τ et µ par les méthodes normalisées ISO1889 et respectivement ISO1888.Thus the wick of the invention comprising more than 4500 filaments can also be characterized by the ratio $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}$

which is greater than an integer value of 9. If it is not easy to count the number of filaments of a wick once the product on the market, on the other hand it is easier to calculate the ratio $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}$

after having measured τ and μ by the standardized methods ISO1889 and ISO1888 respectively.

qui constitue la limite inférieure à laquelle répond une mèche de l'invention. Les filières à plus de 4500 trous (exactement 4410) permettent d'obtenir un rapport de $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}\mathrm{>}\mathrm{9},$

tandis que les filières existantes à 4000 trous ou moins ne remplissent pas cette caractéristique.Figure 2 illustrates a series of curves expressing, according to the title of the wick, the number of filaments as a function of the diameter of the filaments. Has been plotted the reference line $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}=\mathrm{9}$

which constitutes the lower limit to which a wick of the invention responds. The dies with more than 4500 holes (exactly 4410) make it possible to obtain a report of $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}\mathrm{>}\mathrm{9},$

while existing channels with 4000 holes or less do not fulfill this characteristic.

Thus, it is possible by increasing the number of filaments to increase the title of the wick without changing the diameter of the filaments. For 17 μ m, the title is only 2400 tex with a die of 4000 holes while it is 4800 tex (double) for a die 8000 holes.

Moreover, the increase in the number of filaments makes it possible without increasing the titre, to reduce the diameter of the filaments. For 4800 tex, the wick has 24 μm diameter filaments with 4000 filaments, while the diameter is only 17 μm for 8000 filaments.

It is also possible to produce locks with a title of 600 or 900 tex for example, the diameter of the filaments do not exceed 8 or 10 microns respectively.

permet d'obtenir de nouveaux produits par rapport à ceux existants qui présentent:

• à titre identique, une diminution du diamètre des filaments, ce qui permet aux filaments de garder leur souplesse et d'éviter ainsi qu'ils ne se brisent, et par conséquent cela évite l'accumulation de ces filaments brisés sous forme de bourre qui perturbe le fonctionnement des machines et nuit à la régularité d'imprégnation; ou bien
• à diamètre constant, d'augmenter le titre, ce qui permet d'obtenir des renforts plus lourds pour fabriquer ainsi des pièces de plus grandes dimensions nécessitant une plus grande quantité de renfort, ceci sans augmenter le nombre de bobines utilisées, donc sans compliquer la transformation et sans nécessiter de nouvelles installations. Cela améliore la productivité tant pour le fabriquant de fibres que pour le transformateur.

Also, the invention of providing a wick for which $\frac{\mathrm{\tau }}{{\mathrm{\mu }}^{\mathrm{2}}}\mathrm{>}\mathrm{9}$

allows to obtain new products compared to existing ones which present:

• similarly, a decrease in the diameter of the filaments, which allows the filaments to keep their flexibility and thus prevent them from breaking, and therefore it avoids the accumulation of these broken filaments in the form of fluff which disturbs the operation of machines and impairs the regularity of impregnation; or
• constant diameter, to increase the title, which allows to obtain heavier reinforcements to manufacture larger pieces and require a greater amount of reinforcement, without increasing the number of coils used, so without complicating the transformation and without the need for new installations. This improves productivity for both the fiber manufacturer and the processor.

In both cases, it is therefore a question of improving the quality / price ratio. The table below summarizes for various types of applications, the characteristics of the existing locks for their transformation and those obtainable according to the invention. Application Transformation State of the art (4000 filaments) Wick of the invention (8000 filaments) Advantages Wind turbine blades Weaving or manufacture of nonwovens 17 μ m, 2400 tex 17 μ m, 4800 tex productivity, ease of work, large parts Profiles, gratings pultrusion 34 μ m, 9600 tex 24 μ m, 9600 tex flexibility, removal of thorns Rings, profiles Fine pultrusion 12 μ m, 1200tex 12 μ m, 2400 tex productivity, ease of work Automotive construction Thermoplastic extrusion 17 μ m, 2400 tex 17 μ m, 4800 tex productivity, ease of work, impact resistance

The invention is described for a glass fiber wick but it would also be possible to produce a composite wick type Twintex ^® made to the base by the glass filaments issued from the die and in which come to comêler thermoplastic material filaments .

Claims (10)

1. Strand (1) based on glass fibres having a $\frac{\mathit{\tau }}{{\mathit{\mu }}^{\mathrm{2}}}$

   

   ratio greater than 9, where τ is the yardage of the strand in tex and µ is the diameter of the filaments in µm, and comprising at least 6000 filaments, with a yardage higher than 1200 tex, and with a filament diameter higher than 11 µm, said strand coming from a single bushing (13) .
2. Strand according to Claim 1, characterized in that it is a roving (R) directly wounded under the bushing.
3. Strand according to one of the preceding claims, characterized in that it comprises 8000 filaments each 12 µm in diameter and has a yardage of 2400 tex.
4. Strand according to one of the preceding claims, characterized in that it comprises 8000 filaments each 17 µm in diameter and has a yardage of 4800 tex.
5. Strand according to one of the preceding claims, characterized in that it comprises 8000 filaments each 24 µm in diameter and has a yardage of 9600 tex.
6. Strand according to one of the preceding claims, characterized in that it is completely made up of glass filaments.
7. Strand according to one of the claims 1 to 5, characterized in that it is composite and made up of comingled glass filaments and thermoplastic filaments.
8. Use of the strand according to one of the preceding claims for the manufacture of composite materials.
9. Use of the strand according to one of the preceding claims in weaving, pultrusion, extrusion or filament winding methods.
10. Use of the strand according to one of the preceding claims for the manufacture of wind machine blades.

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