DE102009019638A1 - Fabric, in particular for an airbag - Google Patents

Abstract

It describes fabrics, in particular for an airbag, which consists at least partially of hollow filament yarns of polymer material and is characterized in that the fabric has a fabric density DG, calculated according to Prof. Walz, which is equal to the fabric density when using full filament yarns of the same diameter ,

Description

The The present invention relates to a fabric, in particular for an airbag which at least partially consists of hollow filament yarns consists of polymer material.

Such fabrics are for example from the European patent EP 0 616 061 B1 AKZO known, wherein there are disclosed contact or filter fabric woven with different thread densities and different yarn diameters. This initially has the disadvantage that the tissue is still too heavy despite the use of hollow fibers. At this point, the ever-increasing demands of the automobile manufacturers on weight reduction do not need to be particularly addressed.

The full and hollow fibers woven in the woven fabric disclosed therein have the same denier, since the inventor assumed that the required high air permeability and the high-strength fabric required full and hollow fibers of the same yarn strength and thus the same material mass in cross section. Due to the resulting different diameters of full filaments and hollow fibers resulting in processing both types of thread to a textile surface a restless and unevenly thick fabric with different thread density at full filaments (higher thread density) and hollow fibers (thread density lower). It is also unfavorable that such fabrics are difficult to coat evenly. The use of hollow fibers also increases, among other things, the fabric thickness and leads to voluminous airbags with the disadvantage of a higher packing volume. The tissues according to the EP 0 616 061 B1 In certain areas, they also have a different fabric density and thus uneven air permeability. This results in the calculation of fabric density (as opposed to calculation in the EP 0 616 061 B1 ) correctly applied method according to Prof. Walz. A non-uniform air permeability is very unfavorable for a fabric for an airbag, since the determination of the "service life" of the airbag, so the time in which it remains inflated, so its real task is not reliable possible.

It is known to increase the heat capacity of fabrics with hollow fibers or hollow fibers containing them. To use this effect is the EP 0 616 061 B1 Hollow fiber yarns and full-fiber yarns of different thickness, which leads to the disadvantages already mentioned above.

For this complains the EP 0 616 061 B1 moreover, that a hollow area content of over 40% leads to a stiffening of the fiber and thus to a deterioration of the foldability of the airbag fabrics and exemplifies that the yarns wholly or partially composed of hollow fibers have a yarn denier of 200-1100 dtex. Smaller titers are problematic in terms of production performance, and larger titers can not be used because of the then severely deteriorated foldability of the airbag fabrics.

It is important to mention that here the production of hollow filaments by the retention of the Garntiters and an addition of the respective lumen takes place, ie, as a result, the polymer composition in the hollow filament sheath is equal to the polymer mass in the full filament. The lumen is added and increases the thread diameter. This will be in the in the EP 0 616 061 B1 Although fewer threads / cm needed described constructions. The integration (ondulation) of the thicker yarns and thus the resistance to the pulling apart of the weave of warp and weft threads are, however, lower. Furthermore, the thicker the filament walls (annular surface) are, the stronger the hollow filaments are, and thus offer - this is a disadvantage - greater resistance to ondulation.

Of the present invention is based on the object, a tissue for to propose an airbag in which the disadvantages of the prior Technique avoided or at least greatly reduced.

The Task is solved according to the invention a fabric, in particular for an airbag, which at least partially hollow filament yarns of polymeric material and characterized in that the fabric has a fabric density DG, calculated according to Prof. Walz, who has equal the tissue density at use of full filament yarns of the same diameter. With the invention Tissue can be advantageously a property of Use hollow filaments in a targeted manner by increasing the heat capacity or the thermal resistance of the fabric at a constant high density (LD) and high comb extraction force is increased, and this with respect to known tissues of lower weight. Advantageously, remain in the inventive Use of hollow fiber yarns and full fiber yarns the stiffness, the fabric thickness and fabric density constant. The comb extraction force (Measure of the seam strength) increases advantageously even. The fabric according to the invention is suitable especially for air bags or airbags for Passenger restraint systems in vehicles and aircraft.

The fabric according to the invention is due to that the diameter of hollow fiber yarns and full fiber yarns is the same, lighter than a similar to the hollow fibers tissue, wherein the weight reduction corresponds to the lumen percentage. Fortunately, the packing density remains one of the invention Fabric made airbags constant, which is why changes of module dimensions when using the invention Tissues are not required. Another significant advantage results This is because the lower fabric weight is an advantage improved mass acceleration during the highly dynamic Inflation process allows. In addition, the hollow fibers can be the same thickness z. B. in combination with full threads advantageously to process a uniform textile surface.

• – der Garntiter der Hohlfilamente mit zunehmendem Lumen-%-Satz geringer wird,
• – der Garndurchmesser, die Faden- und die Gewebedichte gleich bleiben,
• – die Wandungen der Ringflächen der Hohlfilamente mit zunehmenden Lumen-%-Satz dünner werden und
• – die Formel: Lumen-%-Reduzierung = Gewichtsreduzierung gilt.

The present invention is based on a fabric construction in which

• The yarn denier of the hollow filaments decreases as the lumen% set increases,
• - the yarn diameter, the thread and the fabric density remain the same,
• The walls of the ring surfaces of the hollow filaments become thinner with increasing lumen% set and
• - the formula: Lumen -% - reduction = weight reduction applies.

Definition "Lumen -% - sentence": The lumen percentage gives the proportion of the lumen of a hollow filament in relation to the total cross section of the hollow filament.

While Accordingly, in the case of fabrics known from the prior art, a (negative) Increase in the stiffening of the hollow filaments with increasing Hohlflächenan part is known in the inventive design principle with increasing lumens a thinner Ringflächenwandung Fortunately, the flexural stiffness of the hollow filaments was noted not increased.

With the thinner Ringflächenwandung is the binding the threads of the same diameter as full filaments respectively. For high-density fabrics, the round hollow filaments become round at the binding points the respective deflection by oval bending form, whereby advantageously the resistance to the Kammauszug gets bigger (more frictional resistance).

For example can hollow filaments according to the invention in a thread sequence (warp and / or weft) from solid to hollow filaments, z. B. 1 thread full filament and 1 filament hollow filament are woven.

When using the fabric according to the invention can advantageously also a hollow thread as embroidery (see German Patent DE 101 15 890 B2 ) in particularly thermally stressed zones of a one-piece woven airbag (so-called One-Piece Woven, OPW). This is therefore only possible with the fabric according to the invention, since due to the same diameter of all threads an intolerable thick-thin effect with uneven fabric or OPW surface can be avoided.

In an advantageous embodiment of the invention, the tissue is characterized characterized in that the hollow filament yarns have a lower titer have as full filament yarns of the same diameter and the same polymer, which has many advantages discussed below. So the stiffness, fabric thickness and fabric density are constant. This simplifies the production of uniform Tissues (see above). Also the comb extraction force (measure for the seam strength) is higher than with full filaments comparable tissues.

In A further advantageous embodiment of the invention is the tissue characterized in that it is full filament yarns of the same diameter and the same polymer, and that the hollow filament yarns predefined positions of a web repeat in warp and / or weft are arranged and in relation to screen L1 / 1 höherbindiger Web construction and with higher thread density than one L1 / 1 web design are involved. This advantageously allows the technologically and design-technically targeted arrangement of hollow fiber yarns in z. B. thermally critical areas of a tissue or OPW.

In A further advantageous embodiment of the invention is the tissue characterized in that it is full filament yarns of the same diameter and the same polymer, and that the hollow fibers as Embroidery in thermally stressed zones of one in one Piece of woven airbags (so-called one-piece-woven, ie OPW) are arranged and in relation to screen L1 / 1 höherbindiger Web construction and with higher thread density than one L1 / 1 web design are involved.

In A further advantageous embodiment of the invention is the tissue characterized in that the hollow area portion of Hollow fiber yarns in the range of greater than or equal to 20% is. This hollow area fraction has become in Try proved to be particularly favorable.

In A further advantageous embodiment of the invention is the tissue characterized in that the fabric density according to Prof. Walz [DG%] is greater than 100%. The resulting Strength of the fabric is used in a security component Airbag of particular advantage.

In A further advantageous embodiment of the invention is the tissue characterized in that the fabric density according to Prof. Walz [DG%] is greater than 105%.

In A further advantageous embodiment of the invention is the tissue characterized in that the weight of the fabric when used of hollow filaments compared to solid filaments in the amount of Lumenprozenzsatzes is lower. This compared to the prior art known tissue variants lower weight allows a particularly advantageously improved mass acceleration during the highly dynamic Inflation process of the airbag.

In A further advantageous embodiment of the invention is the tissue characterized in that the for determining the tissue density According to Prof. Walz, relevant effective titers for the induced shrinkage the output titer is.

In A further advantageous embodiment of the invention is the tissue characterized hollow fibers as embroidery in thermal particularly loaded zones of one piece woven Airbags (so-called One-Piece Woven, OPW) enter.

In A further advantageous embodiment of the invention is the tissue characterized in that the polymer material is polyester and a) the yarn diameter (d), b) the thread density per cm, c) the fabric density DG, calculated according to Prof. Walz, d) the tissue thickness and e) the tissue weight that of a woven fabric of polyamide 6.6 solid filaments.

The fabric according to the invention can thus advantageously also be produced with polyester yarns with hollow filaments, with the higher specific gravity of the polyester over the material commonly used today polyamide due to the inventively achievable weight reduction of about 21% by a correspondingly chosen lumen of the hollow fibers is compensated.

In A further advantageous embodiment of the invention is the tissue characterized in that it has a thread density equal to or higher than when using full filaments same Diameter and same Web construction.

in A further advantageous embodiment of the invention is the tissue characterized in that it has a fabric thickness equal to or greater than when using full filament yarns of the same diameter and the same weave construction.

to Clarification is found that with the inventive Fabric is also a one-piece woven airbag (so-called one-piece woven OPW) is meant. It can therefore be an airbag made of an inventive Flat woven fabric with hollow fibers of the same thickness, in thread sequence, chain and / or Shot with solid fibers or manufactured in OPW technology.

Of the Titer of a yarn is defined by the weight of 10,000 m Thread length in grams (dtex). Consequently, the calculated Titers from the base area - with hollow filaments only from the annular surface around the cavity around - the Yarn mass, multiplied by the specific weight and the length of 10,000 m.

The thread diameter d of hollow fibers is calculated from the total base area F _ring plus F _lumen according to the following formula:

Taking into account the lumen percentage [Lumen%], the total area F _ges in mm ^{2 is} calculated from F _ring . The thread diameter d is calculated on the basis of the formula according to Prof. Walz for the calculation of the fabric density as follows:

to The terminology used here for various terms is intended to be the following Explanation serve: Hollow fiber yarns are hollow fibers or synthetic filament yarns with filaments which are hollow inside, with a hollow area proportion, based on the total cross-sectional area the filaments.

The fabric density [DG] after Prof. Walz is defined in "The Tissue Density I" and "The Tissue Density II" in the publication "Textilpraxis" of 1947, pages 330 to 366, Robert Kohlhammer-Verlag, Stuttgart, Germany , The calculation of the fabric density DG requires the determination of the yarn counts, the settings and the knowledge of the density of the pulp used. The calculation of the fabric density DG% according to Prof. Walz:
Fabric density DG% = (d _k + d _s) ² · f _k · f _s
In this case: d _k / d _s = substance diameter of the warp or weft yarn in mm;
f _k / f _s = number of warp threads or weft threads per cm;

The substance diameters of the filaments made of solid filaments are calculated as follows:

{The above formula applies only to plain weaves (fabric density I). Are others, different from the plain weave, hochbindige Bindings - ie bonds or weaving constructions higher as screen L1 / 1 - before, the calculated fabric densities are to multiply with certain factors (eg, twill 2: 1 = 0.70, twill 2: 2 = 0.56, twill 3: 1 = 0.56, Twill 4: 4 = 0.38, Satin 1: 4 = 0.49, Panama 2: 2 = 0.56), man gets the tissue density II.}

interpretation the calculation of tissue density according to the formula of Prof. Walz:

1. Effective titre:

Of the Effective titer calculated at the full thread from the circular area and the hollow thread from the ring surface.

2nd thread diameter:

Of the Thread diameter (d) is relevant for the calculation of Tissue density and results in the case of hollow filaments from the Total cross-sectional area (ring area + hollow area).

3. Correlation of thread thickness, thread density and binding:

The area requirement per bond point (at L1 / 1) results in mm ² from (d _k + d _s ) ² . The quotient of 100 mm ² : (d _k + d _s ) ² corresponds to the max. possible number of bond points per cm ² = 100%. The product of f _k × f _s corresponds to the number of binding points reached per cm ² .

The following explanations are given by way of illustration 1 to 4 supported.

1 schematically shows a section of a woven cartridge.

2 schematically shows an example of a homogeneous polymer plate.

3 schematically shows an example of a "sandwich plate".

4 schematically shows the incorporation of hollow filaments in the warp and weft directions.

1 schematically shows a section of a weave cartridge for the binding L1 / 1 and the associated Sectional view seen in warp and weft direction.

(dK + dS)2×fK×fS = DG% The formula for calculating the fabric density (DG%) according to Prof. Walz is derived from:

(d K + d S ) 2 x f K x f S = DG%

The yarn diameter (d) is the geometrically correct value in [mm] in approach, ie, the substance diameter in solid filaments and the total diameter of ring and hollow surface (F _ges ) in hollow filaments.

The EP 0 616 061 B1 teaches that even with a hollow area content of 20%, an increase in the thermal resistance of about 175% occurs. This statement is based on the following calculation model: The assumed area of 1 m ² with a weight of 210 g / m ² is divided by the specific weight in q / m ³ . The result ( 2 ) is the thickness dv of a homogeneous polymer plate of 1 m ² , in the example listed, of 0.18 mm in PA 6.6.

2 shows an example of a homogeneous polymer plate of 1 m ² area.

The Wall thickness determined in this way is divided by the thermal conductivity (λ) to result in the thermal resistance Rw [K / W] to get the full surface. The thermal resistance (Rw) of the hollow surfaces is based on the same principle, for. B. charged at 20% lumens with two different media.

3 shows an example of a "sandwich plate" of 1 m ² , in which the "outer walls" A enclosing the lumen L of the "thickness" of 0.036 mm have a thickness, ie of 0.09 mm.

Out gives the sum of Rw of the wall + Rw of the hollow surface compared to the approximately 175% higher thermal resistance the full surface. When you consider the thermal resistance of a Full filaments that of a hollow filament with 20% lumens - calculated with the same parameters - then results in a relative increase of Rw by> 300% in the package. In both models, the heat transfer is vertical, or assumed radially to the wall surface.

The model of EP 0 616 061 B1 assumes a closed polymer plate, but does not take into account the design features of a textile surface (binding, ondulation).

The Model based on the present invention on the other hand, on the geometrically correct structure of the package, However, only detects the heat transfer in the radial direction. Taking into account the fabric construction (integration the package, type of binding, DG-%) is the direction of the Heat load based on the package different, d. H. radial to axial. Furthermore must be taken into account that with radial heat load the thermal resistance in the ring surface is lower is as in the lumen and consequently the direction of the heat load not straight.

4 shows the integration of hollow filaments K and S shown in sections in the warp and weft directions schematically shown in section as plain weave (L1 / 1). In the case of an application of heat perpendicular to the textile surface in the direction of arrow V, the heat transfer takes place correspondingly differently to the course of the thread.

This leads to the following advantageous result: If in one textile surface - or in OPWs - both full filaments as well as hollow filaments are processed, then are thermal loaded surfaces, the hollow filaments preferably also in higher-weave constructions, e.g. B. Panama in possibly enter higher weave density or thread density (fabric density II).

Around to show how the invention can be carried out these in the following with reference to embodiments short explained.

There are exemplary embodiments I and II

In Table A above is a comparison of a standard article (only solid fibers) with two embodiments I and II (only hollow fibers) of the fabric according to the invention shown. The substitution of solid filaments by hollow filaments same polymer in a uniformly dense textile surface leads at the same thread diameter (d) to a lower Titer and a lower by the lumen percentage tissue weight.

The high-density fabric "standard articles" (state of the art Technique) consists of polyamide 6.6 (PA 6.6) full filaments and is intended in the same fabric density by a surface construction at least partially substituted from PA6.6 hollow filaments.

The Tightness of the tissue is associated with uncoated because of the LD Use and high seam strength (Kämmausziehkraft) needed. In terms of strength and weight, the fabric is over-engineered according to standard articles.

embodiment I

The Embodiment I starts from an existing PA 6.6 yarn in titers dtex 380/72 with 20% lumens. Considering the specific shrinkage values - the triggered Shrinkage is in a defined relationship to the nominal shrinkage (Hot air shrinkage of the yarn) and is dependent from the finishing process - is about the given tissue density of 106.4% based on Prof. Walz the thread diameter in the finished fabric (after shrinkage) the corresponding Thread density of the finished product (22 × 22 Fd / cm).

The Square meter weight, calculated from thread counts, training and Effective titer (after shrinkage) is around the percentage of the lumen (Lumen -% - rate) lower, and the maximum tensile forces in N / 5 cm reduce accordingly.

The Due to its density, fabric has the required seam strength (Edge comb resistance).

embodiment II

At the Embodiment II is a web of PA 6.6 hollow filaments with exactly the same parameters (DG-%, thread diameter, thread density) made of finished fabric according to "standard article". outgoing from the required effective titre and taking into account the shrinkage value (triggered shrinkage) becomes retrograde the nominal titer as the starting value for the required yarn determined.

The Reduction of the square meter weight corresponds to the lumen percentage, and the maximum tensile forces in the warp and weft directions reduce due to the different thread densities in warp and weft direction by the same percentage same absolute values. In view of a biaxial tensile load of tissue, this equivalence is beneficial. With the embodiment II is the substitution of the so-called standard tissue under improved technical conditions of use (no longer "over engineered", lighter) by a hollow filament fabric possible.

Embodiment III

in the Below, in Table B, yet another embodiment III, the known "standard article from PA 6.6 using polyester hollow filaments with the same Prefabricated tissue parameters is adjusted. The procedure corresponds the embodiment II. This is also possible evidence that the material is polyester because it is more cost-effective, can be used for airbag fabric.

The Fabric (standard article) in a tight construction of PA 6.6, dtex 470, 22 × 21 with DG = 106.4% in L1 / 1 should be the same Density and same thread thickness (thread diameter) under use a corresponding PES hollow filament yarn are produced.

Substitution of solid filaments by hollow filaments of another polymer in a uniform dense textile fabric results in equal denier and fabric weight at the same filament diameter (d) and a lumen percentage which is the percentage difference in specific gravity of both polymers. See Table B. Table B Designation / Dimension PA fabric standard article Fabric made of PES hollow filament Starting titer effective in dtex 474/72 477 lumen% - 20 F ring [mm ² ] - 0.034582 F lumens [mm ² ] - 0.008645 F total [mm ² ] 0.04158 0.043227 D [mm] .2304 .2349 Warp thread [/ dm] 224.8 224.8 Weft thread [/ dm] 209.2 209.2 Incorporation% [warp / weft] 7.11 2.9 / 4.8 Fabric weight [g / m ² ] 239 222 Thread length in [m / m ² ] 4733 4,505.6 Effective titer [dtex] 505 492 F ring [mm ² ] - 0.03565 F lumens [mm ² ] - 0.008645 F total [mm ² ] 0.044295 0.044895 D '[mm] .2378 .2378 Triggered shrinkage [%] 6.14 3 (0,97) DG% 106.4 106.4

Of the Use of the PES hollow filament with 20% lumen (cavity in the fiber) allows the production of a fabric of the same density despite the higher specific gravity (+ 21%) in the same weight class.

Under Consideration of different yarn and shrinkage values and familiarization conditions applies the formula: weight reduction = Lumen%.

Of the Use of hollow filaments of the same diameter in textile surfaces made of solid filaments (mixed structure) result in the same binding construction (eg screen L1 / 1) same fabric thickness with simultaneous weight reduction. In thermally stressed zones, the thread density for Hollow filaments by higher-binder construction with constant Fabric thickness (DG II) are increased accordingly.

Examples:

• a) Flat weave with 1 thread full and 1 thread Hollow filament alternately in warp and weft direction. The tissue becomes easier with the same remaining structure.
• b) flat fabric with predefined locations with hollow filament entry in higher web weave serves the improved Thermal resistance. Entry in chain and / or shot.
• c) Use of hollow filaments as embroidery in OPW - possibly. in a higher weave weave construction - for the purpose of Improvement of thermal resistance.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0616061 B1 [0002, 0003, 0003, 0004, 0005, 0006, 0049, 0054]
• - DE 10115890 B2 [0015]

Cited non-patent literature

• - [DG] according to Prof. Walz is defined in "The Tissue Density I" and "The Tissue Density II" in the publication "Textilpraxis" of 1947, pages 330 to 366, Robert Kohlhammer-Verlag, Stuttgart, Germany [0034]

Claims (14)

Fabric, in particular for an airbag, which consists at least partially of hollow filament yarns of polymer material, characterized in that the fabric has a fabric density DG, calculated according to Prof. Walz, which is equal to the fabric density when using full filament yarns of the same diameter. Fabric according to claim 1, characterized in that the hollow filament yarns have a lower titer than full filament yarns have the same diameter and the same polymer. Fabric according to claim 1 or 2, characterized that the fabric weight in the range of hollow filaments used whose lumen percentage is lower than when using full filaments. Fabric according to claim 1, 2 or 3, characterized the weave construction (weave) is L1 / 1 or higher is. Fabric according to claim 4, characterized in that full filament yarns of the same diameter and same polymer and that the hollow filament yarns at predefined locations a web repeat in chain and / or shot are arranged and in versus L1 / 1 higher-weave weave construction and with higher thread density than with a L1 / 1 weave construction are involved. Fabric according to claim 4, characterized in that full filament yarns of the same diameter and same polymer has, and that the hollow fibers as embroidery in thermal particularly loaded zones of one piece woven Airbags (so-called one-piece-woven, OPW) are arranged and in opposite L1 / 1 higher-weave weave construction and higher Thread density is included as in a L1 / 1 weave construction. Fabric according to one of claims 1 to 6, characterized in that the hollow area proportion or lumen percentage the hollow filament yarns is 20% or higher. Fabric according to one of the preceding claims, characterized in that the fabric density according to Prof. Walz [DG%] is greater than 100%. Fabric according to claim 8, characterized in that the tissue density according to Prof. Walz [DG%] larger than 105%. Fabric according to one of the preceding claims, characterized in that the hollow filament yarns and the full filament yarns Polyester yarns are. The fabric of claim 1, wherein the polymeric material Polyester is, characterized in that a) the yarn diameter (D) b) the thread density per cm, c) the fabric density DG, calculated according to Prof. Walz, d) the fabric thickness and e) the fabric weight that of a woven fabric made of polyamide 6.6 solid filaments correspond. Fabric according to one of the preceding claims, characterized in that the tissue is a uniform Comb puller has. Fabric according to one of the preceding claims, characterized in that it has a thread density equal to or higher than when using full filaments same Diameter and same Web construction. Fabric according to one of the preceding claims, characterized in that the fabric has a fabric thickness which is equal to or greater than when using full filament yarns of the same diameter and the same weave construction.