CA2061810C - Uncoated fabric for manufacturing air bags - Google Patents
Uncoated fabric for manufacturing air bags Download PDFInfo
- Publication number
- CA2061810C CA2061810C CA002061810A CA2061810A CA2061810C CA 2061810 C CA2061810 C CA 2061810C CA 002061810 A CA002061810 A CA 002061810A CA 2061810 A CA2061810 A CA 2061810A CA 2061810 C CA2061810 C CA 2061810C
- Authority
- CA
- Canada
- Prior art keywords
- dtex
- fabric
- air bag
- filament
- linear density
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R21/02—Occupant safety arrangements or fittings, e.g. crash pads
- B60R21/16—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags
- B60R21/23—Inflatable members
- B60R21/235—Inflatable members characterised by their material
-
- D—TEXTILES; PAPER
- D03—WEAVING
- D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
- D03D25/00—Woven fabrics not otherwise provided for
-
- D—TEXTILES; PAPER
- D03—WEAVING
- D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
- D03D1/00—Woven fabrics designed to make specified articles
- D03D1/02—Inflatable articles
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Mechanical Engineering (AREA)
- Woven Fabrics (AREA)
- Air Bags (AREA)
Abstract
Abstract:
Uncoated tightly woven synthetic filament yarn fabric for manufacturing an air bag. The fabric is manufactured from polyamide yarns having a filament linear density of 3.5-4.5 dtex. The air permeability of this fabric is < 10 l/dm2?min and its specific stiffness is < 1.0?10-2.
Uncoated tightly woven synthetic filament yarn fabric for manufacturing an air bag. The fabric is manufactured from polyamide yarns having a filament linear density of 3.5-4.5 dtex. The air permeability of this fabric is < 10 l/dm2?min and its specific stiffness is < 1.0?10-2.
Description
Uncoated fabric for manufacturinq air baqs Akzo nv, Arnhem * * *
Description:
The invention relates to an uncoated tightly woven synthetic filament yarn fabric for manufacturing an air bag.
Fabrics used for manufacturing air bags are required to have in particular a low air pe~neability.
Hitherto a low air permeahility has been mainly achieved by coating the air bag fabric. However, coated fabrics, besides being more expensive to produce, also have appreciable disadvantages in use, of which the increased space required, compared with uncoated fabrics, for accommodation in the steering wheel must be mentioned in particular.
For this reason processe for manufacturing uncoated air bag fabrics have been developed. Here the required low air permeability is achieved through a very tight fabric construction and through special measur~s in finishing such as calendering (e.g. EP-A-314,867) or heat setting (e.g. CA-A-974,745).
It is true that low air permeability is the most important requirement of an air bag fabric, ~ut a serviceable fabric of this kind must additionally meet a number of other important requirements, of which high strength and good foldability are particularly important.
The latter requirement is crucial if the air bag iB to b~
accommodated in the ~teering wheel of motor vehicles in the least amount of space. However, good foldability also make~ possible trouble-free inflation of the air bag for protecting the vehicle occupant in the event of an accident.
To be able to obtain high strengths, air bags have hitherto been manufactured using in particular y~rns having a high filament linear density. For instance, US-A3,842,583 propoees for this purpo~e yarn~ having a filament linear density of 6.0-6.2 den (6.6-6.8 dtex).
CA-A-974,745 proposes a yarn having a filament linear density of 6 den (6.~ dtex).
Although US-A-4,977,016 specifies a yarn linear density range of 400-600 den ~440-660 dtex) for 100-300 individual filaments, the invention is described in the embodiment examples only in terms of a yarn ha~ing a linear density of 440 den and 100 individual filaments, which corresponds to a filament linear density of 4.4 den (4.8 dtex).
- It is true that these linear densities give the required strength, but they have the appreciable dis-advantage of high stifness, which has a ~ery adverse effect on foldability. The least-space requirement for accommodating the air bag, for example in the steering wheel of the vehicle, and trouble-free inflation cannot - be adequately achieved with linear densities of this order of magnitude.
Similarly, very low filament linear densities have already been proposed for manufacturing air bag fabrics. For instance, JP-A-64-041,438 proposes for this purpose linear densities below 3 den (3.3 dtex) and even prefers linear densities below 2 den (2.2 dtex). It is true that these linear densities are free of the problem of inadequate foldability, but they do have appreciable disadvantages as regards economics. For in~tance, in man-made fibre spinning, fine linear densities are more expensive to produce than coarse linear densities.
Moreover, more filament breakages occur at the drawing stage, resulting in a fluffy material of little suitability for further processing by weaving. This disadvantage is particularly notic~able when weaving a - very tight fabric construction as required for air bag fabrics. When procsssing yarns of such fine filament linear densities it is therefore inevitable that the weaving efficiency will be lower. Finally, very fine linear densities are also more problematical than coarse linear densities in regard to abrasion resistance along the folds of the folded air bag.
8 i ~
_ 3 AGW2318 It is therefore an object of the present invention to develop a fabric for manufacturing air bags which:Eully meets ~e air bag fabric ~e ~ rements such as lcw a~ permeability, high strength and high abrasion resistance at the folds, which makes possible ~oft cushioning of the vehicle occupants in the event of an accident J and which moreover is inexpensive to manufacture and further process.
It has now been found, surprisingly, that these requirements can be satisfactorily met only with poly-amide yarns of precisely selscted filament linear densities. This is because only if polyamide yarns having a filament linear density of 3.5-4.5 dtex are used does the fabric obtained fully guarantee the proper~ies required of air bag fabrics in respect of air permea-bility, strength, abrasion resistance of the folds and in particular foldability. Polyamide yarns having this linear density can be manufactured inexpensively and are free of the lints which in the case of finer fila-ment linear densities customarily impair yarn quality as a consequence of stretch breakages.
Furthermore, polyamide yarns having a filament linear density of 3.5-4.5 dtex additionally offer ~he particular ad~antage of lower air permeability compared with yarns of equal yarn but higher filament linear densities. This means that such polyamide yarns make it possible to use fewer threads in the fabric and yet, through suitable finishin~ conditions, ob~ain a fabric having the low air permeability required for air bags.
Thus, these polyamide yarns, compared with the yarns of higher filament linear density, yield a distinct cos~
benefit in fabric manufacture.
Suitable yarn linear densities range from 200 to 600 dtex. Experiments were carried out with polyamide yarns of 235 dtex and 72 filaments (235 f 72 ^ filament linear density 3.3 dte~), 350 f 94 (filament linear density 3.8 dtex) and 470 f 104 (filament linear density 4.5 dtex).
The polyamide yarns to be used for manu-facturing air bag fabrics preferably have a tenacity of at lea~t 2 ~
60 cN/tex and an elongation of 15-30%. This meets speci-fications issued by the automotive manufacturers in a particularly advantageous manner.
Air bag fabrics can be manufactured with any synthetic filament yarn which meets the abovPmentioned tenacity and elongation values. ~owe~er, polyamide yarns have been found to be particularly highly suitable.
Compared with for example polyester yarns they have the significant advantage of higher elasticity, which is due to a flatter course of the load-extension line in the initial region. Of particular suit~bility for use in air bag fabrics are yarns made of nylon 6.6. Particular preference is given here to yarns made of nylon 6.6 which contain a heat stabiliser introduced in the course of the polycondensation.
The fabrics are manufactured in a tight con-struction, preferably in a plain or Panama weave. How-ever, it is also possible to use twill weaves. In the case of a polyamide yarn linear density of 235 dtex, 26~30 threads per cm are used in warp and weft. If the polyamide yarn has a linear density of 350 dtex, 23-27 threads per cm are used. If polyamide yarns having a linear density of 470 dtex are used, then 19-23 threads per cm are employed. The numbers quoted here relate to a plain weave. In the case of a Panama weave with a yarn linear density of 235 dtex the numbers are for example 34-38 threads per cm in warp and weft.
An important requirement is an essentially symmetrical fabric sett; that is, the fabric must have the same or virtually the same number of threads per cm in both warp and weft. Only such setts make it possible to meet the automotive manufacturers' demands for equal strength in warp and weft.
The desired air permeability is achieved with the aid of a wet process, described in EP-A 436,950. It involves shrinking in an aqueous bath within the temperature range between 60-140C. This is followed by drying only and no heat setting. The precondition for this process is that the polyamide yarns used have a hot 2 ~
air shrinkage of at least 6% (measured at 190C).
Air bag fabric i9 required, according to the automotive manufacturers' specificati~ns, to have an air permeability of ~ 10 l/dm2 min at ~ test pressure dif-ference of 500 Pa. This requirement applies to tnecontact part of the air bag. The filter part i5 permitted to have air permeahilities of 20 ao l/dm2-min. The fabrics manufactured according to the present invention readily meet even the very low air permeability required for the contact part of the air bag.
As shown in the following table, the fabrics manufactured according to the present invention from polyamide yarns having a filament linear density of 3.5-4.5 dtex always give a lower air permeability than if polyamide yarns of higher filament linear densities are used:
Yarn Fila~ent linear Threads per cm Air permeability type density dtex warp weft l/dm2 min at 500 Pa 235 f 36 6.5 28.8 27.9 7.7 235 f 72 3.3 27.8 27.7 3.1 ~` 350 f 72 4.9 25.2 25.7 5.8 ~ 350 f 94 3.8 25.0 24.6 4.1 :~ 470 f 72 6.5 21.3 21.1 7.5 470 f 1044.5 20.7 21.1 4.5 The comparative experiments recited in this table were each carried out with the same number of threads for the polyamide yarns having finer and coarser filament linear densities. Further experiments h~ve shown that the number of threads per cm can be reduced on average by 2 in warp and we~t if polyamide yarns having a fil~ment linear density of 3~5-4.5 dtex are used in place of the hitherto customary polyamide yarns having a filament linear density of 5.0-6.5 dtex. Even with this fewer number of threads it is still no problem to achieve the required air permeabilities of ~ 10 l/dm2 min. Conse-quently, by using polyamide yarn~ having a filament $ ~ ~
linear density of 3.5-4.5 dtex instead of the hitherto used polyamide yarns having a filament linear density of 5.0-6.5 dtex, it is possible to achieve a cost saving at the fabric manufacturing stage.
5The air permeability of the fabrics according to the present invention was tested on the lines of DIN 53887. However, in departure from this DIN standard the test pressure difference was raised to 500 Pa in order that a discernible test signal was still obtainable 10with the fabrics manufactured according to the present invention.
A linear density of 3.5-4.5 dtex haq a particu-larly advantageous effect on the ~oldability of air bag fabrics. This lower filament linear density compared with 15the polyamide yarn hitherto predominantly used ~filament linear density > 5 dtex) brings about a reduction in the stiffness of the air bag fabric, thereby distinctly improving the foldability. Consequently, less space is required to accommodate the air bag in the motor vehicle, 20for example in the steering wheel. Moreover, however, a low stiffness and hence better foldability of the air bag fabric also brings about trouble-free inflation of the air bag in the event of the air bag function being triggered, thereby improving in a particularly advan-25tageous manner the protective effect of the air bag on the vehicle occupants in the event of an impact. This is of particular importance in the event of out-of-position contact when the seat position of the vehicle occupant differs from the standard position. If the air bag 30function is triggered in this situation, air bags manu-factured with polyamide yarns having filament linear densities > 5 dtex give rise to a sudden impact of the inflated air bag on the vehicle occupant with an atten-dant risk of injury, while, if air bag fabrics made of 35polyamide yarns having fil~ment linear densities of 3.5-4.5 dtex are used, th~ higher 1exibility of the fabric and hence the better adaptability to the body shape of the vehicle occupant makes a softer cushioning possible. Very particular advantages have been found to 2 ~ ~ A 8 ~ ~
~ 7 ~ AGW2318 be possessed here by fabrics made of polyamide yarns having a filament linear density of 3.5-4.5 dtex, ~ince, compared with polyester fox examyle, polyamide has a higher flexibility and thus the positive effect of yarns having a filament linear den~ity of 3~5-4O 5 dtex is additionally enhanced by the high flexibility of the polyamide.
The lower stiffness and hence better foldability of fabrics made of polyamide ya~ns having a filament linear density of 3.5-4.5 dtex compared with-fabrics made of the hitherto used polyamide yarns having a filament linear density > 5 dtex is shown in the following table:
Yarn type Filament linear density Specific stiffness - dtex - -; 235 f 36 6.5 1.35-10-2 235 f 72 3.3 0~68-10-2 350 f 72 4.9 0 95 10-2 350 f 94 3.8 0.80-10-2 470 f 72 6.5 1.32-10-2 470 f 104 4.5 0.88-10-2 The test fabrics were manufactured in a plain weave with the number~ of threads per cm in accordance with the a~o~e-stated particulars.
The bending stiffness was tested with a Taber stiffness tester, Model 150 B, from Taber In~truments.
This instrument determines the moment needed to deflect the end of a sample 3% mm in width and 50 mm in length, clamped at one end, through an angle of 15. The unit of measurement is the stiffness unit (SU). 1 SU is the bending moment (in cN-cm) of a sheetlike te t specimen of : the stated width which i5 being deflected through 15.
Contrary to the customary clamped length of 50 mm, however, the abovementioned experiment~ were carried out with a clamped length of 10 Imm.
To enable an objective comparison to be made between di~ferent fabrics, the specific ~tiffness was calculated according to the following formula:
Bending stiffness x air permeability Specific stiffness =
5Linear density In addition to the stiffness unit SU determined by the abovementioned method, the speci:Eic stiffness is affected by the yarn linear density and the air per-meability as an indirect measure of the fabric density.
10It is true that a further reduction in the Eilament linear density results in a further reduction in the stiffness of the fabric and further improved foldability, but, if polyamide yarns having a filament linear density < 3.5 dtex are used, the yarn quality : 15deteriorates very considerably, a~ the following tabl~ of lint measurements shows:
.: Yarn type Filament linear density lint~ per t dtex 235 f 36 6.5 350 ~ 235 f 72 3.3 1800 470 f 72 6.5 300 t ~70 ~ 104 4.5 800 The fact that polyamide yarn~ having a ilament 25lineax density below 3.5 dtex have greatly increa~ed number~ of li~ts mean~ that such fine-filament yarns cannot be u~ed for manufacturing air bags.
The choice of a filament linear den~ity of . 3.5-4.5 dtex for the polyamide yarns envi~aged for air .~ 30bag manufacture re~ult~ in an air bag ~ystem which is ; safer than that of the priGr art. Fabrics manufactured from these polyamide yarns readily meet the automotive manu~acturers' demand~ for high strength and low air per-meability. In addition, the higher flexibility and better 35unfoldability on triggering of the air bag function with the fabric~ manufactured a~cording to the pre3ent - 9 - AG~2318 invention give safer cushioning of the vehicle occupant.
~bodiment examples Example 1 A 235-dtex 72 fii~ment nylon 6.6 yarn, the filament linear density accordingly being 3.3 dtex, was used to manufacture an air ~ag fabric by plain weaving with 28 threads per cm in warp and weftO The fabric was treated in an aqueous bath on a jigger to shrinking.
The treatment was started at 40C and the treatment temperature was raised to 95C. The actual shrinking took place at that temperature. The fabric was then dried on a stenter at 150C. The fabric was found to ha~e an air permeability of 3.1 l/dm2 min and a specific stiffness of 0.68 10-2.
A comparative experiment with a 235-dtex 36-filament yarn, corresponding to a filament linear density of 6.5 dte~, under the same manufacturing conditions in weaving and the same finishing conditions gave an air permeability of 7.7 l/dm2 min and a specific stiffness of 1.35 10-2.
Example 2:
A 350-dtex 94-filament nylon 6.6 yarn, which accordingly had a filament linear density of 3.8 dtex, was used to manufacture an air bag fabric by plain wea~ing with 25 threads per cm in warp and weft. The wet treatment and drying were carried out as in Example l.
- The abric was found to ha~e an air permeability of 4.1 l/dm2 min and a speciflc stiffness of 0.80 10-2.
A comparative experiment with a 350-dtex 72-filament yarn, corresponding to a filament linear density of 4.9 dtex, under the same manufacturing conditions in weavlng and the ~ame finishing conditions gave an air permeability of 5.8 l/dm2 min and a specific stiffness of 0.95 1~-2.
~xample 3:
A 470~dtex 104-filament nylon 6.6 yarn, which according].y had a filament linear density of 4.5 dtex, was used to manufacture an air bag fabric by plain weaving with 21 threads per cm in warp and weft. The wet treatment and drying were carried out as in Example 1.
The fabric was found to have an air permeability of 4.5 l/dm2 min and a specific stiffness of 0.88-10-2.
A comparative experiment with a 470-dtex 72-filament yarn, corresponding to a filament linear density of 6.5 dtex, under the same manufacturing conditions in - 10 weaving and the same finishing conditions gave an air permeability of 7.5 l/dm2 min and a specific stiffness of 1.32 10-2.
, ... .
;",' :, -
Description:
The invention relates to an uncoated tightly woven synthetic filament yarn fabric for manufacturing an air bag.
Fabrics used for manufacturing air bags are required to have in particular a low air pe~neability.
Hitherto a low air permeahility has been mainly achieved by coating the air bag fabric. However, coated fabrics, besides being more expensive to produce, also have appreciable disadvantages in use, of which the increased space required, compared with uncoated fabrics, for accommodation in the steering wheel must be mentioned in particular.
For this reason processe for manufacturing uncoated air bag fabrics have been developed. Here the required low air permeability is achieved through a very tight fabric construction and through special measur~s in finishing such as calendering (e.g. EP-A-314,867) or heat setting (e.g. CA-A-974,745).
It is true that low air permeability is the most important requirement of an air bag fabric, ~ut a serviceable fabric of this kind must additionally meet a number of other important requirements, of which high strength and good foldability are particularly important.
The latter requirement is crucial if the air bag iB to b~
accommodated in the ~teering wheel of motor vehicles in the least amount of space. However, good foldability also make~ possible trouble-free inflation of the air bag for protecting the vehicle occupant in the event of an accident.
To be able to obtain high strengths, air bags have hitherto been manufactured using in particular y~rns having a high filament linear density. For instance, US-A3,842,583 propoees for this purpo~e yarn~ having a filament linear density of 6.0-6.2 den (6.6-6.8 dtex).
CA-A-974,745 proposes a yarn having a filament linear density of 6 den (6.~ dtex).
Although US-A-4,977,016 specifies a yarn linear density range of 400-600 den ~440-660 dtex) for 100-300 individual filaments, the invention is described in the embodiment examples only in terms of a yarn ha~ing a linear density of 440 den and 100 individual filaments, which corresponds to a filament linear density of 4.4 den (4.8 dtex).
- It is true that these linear densities give the required strength, but they have the appreciable dis-advantage of high stifness, which has a ~ery adverse effect on foldability. The least-space requirement for accommodating the air bag, for example in the steering wheel of the vehicle, and trouble-free inflation cannot - be adequately achieved with linear densities of this order of magnitude.
Similarly, very low filament linear densities have already been proposed for manufacturing air bag fabrics. For instance, JP-A-64-041,438 proposes for this purpose linear densities below 3 den (3.3 dtex) and even prefers linear densities below 2 den (2.2 dtex). It is true that these linear densities are free of the problem of inadequate foldability, but they do have appreciable disadvantages as regards economics. For in~tance, in man-made fibre spinning, fine linear densities are more expensive to produce than coarse linear densities.
Moreover, more filament breakages occur at the drawing stage, resulting in a fluffy material of little suitability for further processing by weaving. This disadvantage is particularly notic~able when weaving a - very tight fabric construction as required for air bag fabrics. When procsssing yarns of such fine filament linear densities it is therefore inevitable that the weaving efficiency will be lower. Finally, very fine linear densities are also more problematical than coarse linear densities in regard to abrasion resistance along the folds of the folded air bag.
8 i ~
_ 3 AGW2318 It is therefore an object of the present invention to develop a fabric for manufacturing air bags which:Eully meets ~e air bag fabric ~e ~ rements such as lcw a~ permeability, high strength and high abrasion resistance at the folds, which makes possible ~oft cushioning of the vehicle occupants in the event of an accident J and which moreover is inexpensive to manufacture and further process.
It has now been found, surprisingly, that these requirements can be satisfactorily met only with poly-amide yarns of precisely selscted filament linear densities. This is because only if polyamide yarns having a filament linear density of 3.5-4.5 dtex are used does the fabric obtained fully guarantee the proper~ies required of air bag fabrics in respect of air permea-bility, strength, abrasion resistance of the folds and in particular foldability. Polyamide yarns having this linear density can be manufactured inexpensively and are free of the lints which in the case of finer fila-ment linear densities customarily impair yarn quality as a consequence of stretch breakages.
Furthermore, polyamide yarns having a filament linear density of 3.5-4.5 dtex additionally offer ~he particular ad~antage of lower air permeability compared with yarns of equal yarn but higher filament linear densities. This means that such polyamide yarns make it possible to use fewer threads in the fabric and yet, through suitable finishin~ conditions, ob~ain a fabric having the low air permeability required for air bags.
Thus, these polyamide yarns, compared with the yarns of higher filament linear density, yield a distinct cos~
benefit in fabric manufacture.
Suitable yarn linear densities range from 200 to 600 dtex. Experiments were carried out with polyamide yarns of 235 dtex and 72 filaments (235 f 72 ^ filament linear density 3.3 dte~), 350 f 94 (filament linear density 3.8 dtex) and 470 f 104 (filament linear density 4.5 dtex).
The polyamide yarns to be used for manu-facturing air bag fabrics preferably have a tenacity of at lea~t 2 ~
60 cN/tex and an elongation of 15-30%. This meets speci-fications issued by the automotive manufacturers in a particularly advantageous manner.
Air bag fabrics can be manufactured with any synthetic filament yarn which meets the abovPmentioned tenacity and elongation values. ~owe~er, polyamide yarns have been found to be particularly highly suitable.
Compared with for example polyester yarns they have the significant advantage of higher elasticity, which is due to a flatter course of the load-extension line in the initial region. Of particular suit~bility for use in air bag fabrics are yarns made of nylon 6.6. Particular preference is given here to yarns made of nylon 6.6 which contain a heat stabiliser introduced in the course of the polycondensation.
The fabrics are manufactured in a tight con-struction, preferably in a plain or Panama weave. How-ever, it is also possible to use twill weaves. In the case of a polyamide yarn linear density of 235 dtex, 26~30 threads per cm are used in warp and weft. If the polyamide yarn has a linear density of 350 dtex, 23-27 threads per cm are used. If polyamide yarns having a linear density of 470 dtex are used, then 19-23 threads per cm are employed. The numbers quoted here relate to a plain weave. In the case of a Panama weave with a yarn linear density of 235 dtex the numbers are for example 34-38 threads per cm in warp and weft.
An important requirement is an essentially symmetrical fabric sett; that is, the fabric must have the same or virtually the same number of threads per cm in both warp and weft. Only such setts make it possible to meet the automotive manufacturers' demands for equal strength in warp and weft.
The desired air permeability is achieved with the aid of a wet process, described in EP-A 436,950. It involves shrinking in an aqueous bath within the temperature range between 60-140C. This is followed by drying only and no heat setting. The precondition for this process is that the polyamide yarns used have a hot 2 ~
air shrinkage of at least 6% (measured at 190C).
Air bag fabric i9 required, according to the automotive manufacturers' specificati~ns, to have an air permeability of ~ 10 l/dm2 min at ~ test pressure dif-ference of 500 Pa. This requirement applies to tnecontact part of the air bag. The filter part i5 permitted to have air permeahilities of 20 ao l/dm2-min. The fabrics manufactured according to the present invention readily meet even the very low air permeability required for the contact part of the air bag.
As shown in the following table, the fabrics manufactured according to the present invention from polyamide yarns having a filament linear density of 3.5-4.5 dtex always give a lower air permeability than if polyamide yarns of higher filament linear densities are used:
Yarn Fila~ent linear Threads per cm Air permeability type density dtex warp weft l/dm2 min at 500 Pa 235 f 36 6.5 28.8 27.9 7.7 235 f 72 3.3 27.8 27.7 3.1 ~` 350 f 72 4.9 25.2 25.7 5.8 ~ 350 f 94 3.8 25.0 24.6 4.1 :~ 470 f 72 6.5 21.3 21.1 7.5 470 f 1044.5 20.7 21.1 4.5 The comparative experiments recited in this table were each carried out with the same number of threads for the polyamide yarns having finer and coarser filament linear densities. Further experiments h~ve shown that the number of threads per cm can be reduced on average by 2 in warp and we~t if polyamide yarns having a fil~ment linear density of 3~5-4.5 dtex are used in place of the hitherto customary polyamide yarns having a filament linear density of 5.0-6.5 dtex. Even with this fewer number of threads it is still no problem to achieve the required air permeabilities of ~ 10 l/dm2 min. Conse-quently, by using polyamide yarn~ having a filament $ ~ ~
linear density of 3.5-4.5 dtex instead of the hitherto used polyamide yarns having a filament linear density of 5.0-6.5 dtex, it is possible to achieve a cost saving at the fabric manufacturing stage.
5The air permeability of the fabrics according to the present invention was tested on the lines of DIN 53887. However, in departure from this DIN standard the test pressure difference was raised to 500 Pa in order that a discernible test signal was still obtainable 10with the fabrics manufactured according to the present invention.
A linear density of 3.5-4.5 dtex haq a particu-larly advantageous effect on the ~oldability of air bag fabrics. This lower filament linear density compared with 15the polyamide yarn hitherto predominantly used ~filament linear density > 5 dtex) brings about a reduction in the stiffness of the air bag fabric, thereby distinctly improving the foldability. Consequently, less space is required to accommodate the air bag in the motor vehicle, 20for example in the steering wheel. Moreover, however, a low stiffness and hence better foldability of the air bag fabric also brings about trouble-free inflation of the air bag in the event of the air bag function being triggered, thereby improving in a particularly advan-25tageous manner the protective effect of the air bag on the vehicle occupants in the event of an impact. This is of particular importance in the event of out-of-position contact when the seat position of the vehicle occupant differs from the standard position. If the air bag 30function is triggered in this situation, air bags manu-factured with polyamide yarns having filament linear densities > 5 dtex give rise to a sudden impact of the inflated air bag on the vehicle occupant with an atten-dant risk of injury, while, if air bag fabrics made of 35polyamide yarns having fil~ment linear densities of 3.5-4.5 dtex are used, th~ higher 1exibility of the fabric and hence the better adaptability to the body shape of the vehicle occupant makes a softer cushioning possible. Very particular advantages have been found to 2 ~ ~ A 8 ~ ~
~ 7 ~ AGW2318 be possessed here by fabrics made of polyamide yarns having a filament linear density of 3.5-4.5 dtex, ~ince, compared with polyester fox examyle, polyamide has a higher flexibility and thus the positive effect of yarns having a filament linear den~ity of 3~5-4O 5 dtex is additionally enhanced by the high flexibility of the polyamide.
The lower stiffness and hence better foldability of fabrics made of polyamide ya~ns having a filament linear density of 3.5-4.5 dtex compared with-fabrics made of the hitherto used polyamide yarns having a filament linear density > 5 dtex is shown in the following table:
Yarn type Filament linear density Specific stiffness - dtex - -; 235 f 36 6.5 1.35-10-2 235 f 72 3.3 0~68-10-2 350 f 72 4.9 0 95 10-2 350 f 94 3.8 0.80-10-2 470 f 72 6.5 1.32-10-2 470 f 104 4.5 0.88-10-2 The test fabrics were manufactured in a plain weave with the number~ of threads per cm in accordance with the a~o~e-stated particulars.
The bending stiffness was tested with a Taber stiffness tester, Model 150 B, from Taber In~truments.
This instrument determines the moment needed to deflect the end of a sample 3% mm in width and 50 mm in length, clamped at one end, through an angle of 15. The unit of measurement is the stiffness unit (SU). 1 SU is the bending moment (in cN-cm) of a sheetlike te t specimen of : the stated width which i5 being deflected through 15.
Contrary to the customary clamped length of 50 mm, however, the abovementioned experiment~ were carried out with a clamped length of 10 Imm.
To enable an objective comparison to be made between di~ferent fabrics, the specific ~tiffness was calculated according to the following formula:
Bending stiffness x air permeability Specific stiffness =
5Linear density In addition to the stiffness unit SU determined by the abovementioned method, the speci:Eic stiffness is affected by the yarn linear density and the air per-meability as an indirect measure of the fabric density.
10It is true that a further reduction in the Eilament linear density results in a further reduction in the stiffness of the fabric and further improved foldability, but, if polyamide yarns having a filament linear density < 3.5 dtex are used, the yarn quality : 15deteriorates very considerably, a~ the following tabl~ of lint measurements shows:
.: Yarn type Filament linear density lint~ per t dtex 235 f 36 6.5 350 ~ 235 f 72 3.3 1800 470 f 72 6.5 300 t ~70 ~ 104 4.5 800 The fact that polyamide yarn~ having a ilament 25lineax density below 3.5 dtex have greatly increa~ed number~ of li~ts mean~ that such fine-filament yarns cannot be u~ed for manufacturing air bags.
The choice of a filament linear den~ity of . 3.5-4.5 dtex for the polyamide yarns envi~aged for air .~ 30bag manufacture re~ult~ in an air bag ~ystem which is ; safer than that of the priGr art. Fabrics manufactured from these polyamide yarns readily meet the automotive manu~acturers' demand~ for high strength and low air per-meability. In addition, the higher flexibility and better 35unfoldability on triggering of the air bag function with the fabric~ manufactured a~cording to the pre3ent - 9 - AG~2318 invention give safer cushioning of the vehicle occupant.
~bodiment examples Example 1 A 235-dtex 72 fii~ment nylon 6.6 yarn, the filament linear density accordingly being 3.3 dtex, was used to manufacture an air ~ag fabric by plain weaving with 28 threads per cm in warp and weftO The fabric was treated in an aqueous bath on a jigger to shrinking.
The treatment was started at 40C and the treatment temperature was raised to 95C. The actual shrinking took place at that temperature. The fabric was then dried on a stenter at 150C. The fabric was found to ha~e an air permeability of 3.1 l/dm2 min and a specific stiffness of 0.68 10-2.
A comparative experiment with a 235-dtex 36-filament yarn, corresponding to a filament linear density of 6.5 dte~, under the same manufacturing conditions in weaving and the same finishing conditions gave an air permeability of 7.7 l/dm2 min and a specific stiffness of 1.35 10-2.
Example 2:
A 350-dtex 94-filament nylon 6.6 yarn, which accordingly had a filament linear density of 3.8 dtex, was used to manufacture an air bag fabric by plain wea~ing with 25 threads per cm in warp and weft. The wet treatment and drying were carried out as in Example l.
- The abric was found to ha~e an air permeability of 4.1 l/dm2 min and a speciflc stiffness of 0.80 10-2.
A comparative experiment with a 350-dtex 72-filament yarn, corresponding to a filament linear density of 4.9 dtex, under the same manufacturing conditions in weavlng and the ~ame finishing conditions gave an air permeability of 5.8 l/dm2 min and a specific stiffness of 0.95 1~-2.
~xample 3:
A 470~dtex 104-filament nylon 6.6 yarn, which according].y had a filament linear density of 4.5 dtex, was used to manufacture an air bag fabric by plain weaving with 21 threads per cm in warp and weft. The wet treatment and drying were carried out as in Example 1.
The fabric was found to have an air permeability of 4.5 l/dm2 min and a specific stiffness of 0.88-10-2.
A comparative experiment with a 470-dtex 72-filament yarn, corresponding to a filament linear density of 6.5 dtex, under the same manufacturing conditions in - 10 weaving and the same finishing conditions gave an air permeability of 7.5 l/dm2 min and a specific stiffness of 1.32 10-2.
, ... .
;",' :, -
Claims (5)
1. Uncoated tightly woven synthetic filament yarn fabric for manufacturing an air bag, characterized in that the yarn used for this purpose is a polyamide yarn and has a filament linear density of 3.5-4.5 dtex, an air permeability < 10 1/dm2~min and a specific stiffness < 1.0~10 -2, said air permeability being obtained by shrinking in a wet process.
2. Fabric according to claim 1 characterized in that the polyamide yarn used for this purpose has a linear density of 200-600 dtex.
3. Fabric according to claims 1 to 2 characterized in that the fabric has an at least essentially symmetrical sett.
4. Air bag made of a fabric according to any one of claims 1 to 3.
5. Air bag system using an air bag of a fabric according to any one of claims 1 to 3.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4105943.3 | 1991-02-26 | ||
| DE4105943 | 1991-02-26 | ||
| DEP4200161.7 | 1992-01-07 | ||
| DE4200161 | 1992-01-07 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2061810A1 CA2061810A1 (en) | 1992-08-27 |
| CA2061810C true CA2061810C (en) | 2000-05-30 |
Family
ID=25901360
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002061810A Expired - Lifetime CA2061810C (en) | 1991-02-26 | 1992-02-25 | Uncoated fabric for manufacturing air bags |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0501295B1 (en) |
| JP (1) | JPH0559632A (en) |
| KR (1) | KR920016632A (en) |
| AU (2) | AU653984B2 (en) |
| CA (1) | CA2061810C (en) |
| DE (1) | DE59207564D1 (en) |
| ES (1) | ES2094833T3 (en) |
| SG (1) | SG87724A1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE59403094D1 (en) * | 1993-03-17 | 1997-07-17 | Schweizerische Viscose | FILTER FABRIC FOR GAS PILLOWS |
| US5768875A (en) * | 1993-03-17 | 1998-06-23 | Rhone-Poulenc Viscosuisse S.A. | Filter fabric with core sheating thread, and a bag produced therefrom |
| ES2106389T3 (en) * | 1993-03-19 | 1997-11-01 | Akzo Nobel Nv | AIR AND FABRIC CUSHION FOR ITS MANUFACTURE. |
| US5503197A (en) * | 1994-03-30 | 1996-04-02 | Milliken Research Corporation | Method for producing high weave density airbag fabric on a water-jet loom using unsized yarns |
| US5421378A (en) * | 1994-03-30 | 1995-06-06 | Milliken Research Corporation | Airbag weaving on a water-jet loom using yarns |
| ATE171900T1 (en) * | 1994-08-25 | 1998-10-15 | Rhodia Filtec Ag | UNCOATED FABRIC FOR AIRBAG |
| ES2116181B1 (en) * | 1994-12-05 | 1999-03-01 | Autotex S A | MANUFACTURING PROCEDURE FOR A LOW AIR PERMEABILITY INDUSTRIAL FABRIC AND CORRESPONDING MACHINE. |
| ES2133860T3 (en) * | 1995-04-22 | 1999-09-16 | Akzo Nobel Nv | YARN CONSTITUTED BY INTERLOCKING SYNTHETIC FILAMENTS FOR THE PRODUCTION OF TECHNICAL FABRICS. |
| AR010847A1 (en) * | 1997-01-20 | 2000-07-12 | Rhone Poulenc Filtec Ag | TECHNICAL FABRIC IN PARTICULAR, FOR AIR BAGS, AND METHOD FOR THE MANUFACTURE OF FILAMENT THREAD FOR FABRIC. |
| US5881776A (en) * | 1997-01-24 | 1999-03-16 | Safety Components Fabric Technologies, Inc. | Rapier woven low permeability air bag fabric |
| US6022817A (en) * | 1997-06-06 | 2000-02-08 | E. I. Du Pont De Nemours And Company | Fabric for airbag |
| JP3767173B2 (en) * | 1998-06-09 | 2006-04-19 | タカタ株式会社 | Air belt bag |
| CA2450103C (en) | 2003-10-22 | 2008-09-16 | Hyosung Corporation | Low shrinkage polyamide fiber and uncoated fabric for airbags made of the same |
| KR100451263B1 (en) * | 2003-12-30 | 2004-10-11 | 주식회사 효성 | Polyamide fibers for uncoated airbag |
| US7581568B2 (en) | 2006-02-07 | 2009-09-01 | International Textile Group, Inc. | Water jet woven air bag fabric made from sized yarns |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA974745A (en) * | 1972-04-25 | 1975-09-23 | Clifford Hoyle | Low permeability woven fabric |
| US3842583A (en) * | 1972-06-30 | 1974-10-22 | Du Pont | Yarn and inflatable bag made therefrom |
| DE8714595U1 (en) * | 1987-11-03 | 1988-01-28 | Bloch, Klaus, 5205 St Augustin | Airbag for motor vehicles |
| US4977016B1 (en) * | 1988-10-28 | 1998-03-03 | Stern & Stern Ind Inc | Low permeability fabric and method of making same |
| DE59006012D1 (en) * | 1989-09-07 | 1994-07-14 | Akzo Nobel Nv | Uncoated fabric for airbags. |
| DE59001559D1 (en) * | 1990-01-12 | 1993-07-01 | Akzo Nv | METHOD FOR THE PRODUCTION OF UNCOATED TECHNICAL FABRICS WITH LOW AIR PLANTABILITY. |
| DE4004216A1 (en) * | 1990-02-12 | 1991-08-14 | Hoechst Ag | FABRIC FOR AN AIRBAG |
| DE4026374A1 (en) * | 1990-04-25 | 1991-10-31 | Kolbenschmidt Ag | GAS BAG FOR AIRBAG SYSTEMS |
-
1992
- 1992-02-19 SG SG9502082A patent/SG87724A1/en unknown
- 1992-02-19 ES ES92102740T patent/ES2094833T3/en not_active Expired - Lifetime
- 1992-02-19 DE DE59207564T patent/DE59207564D1/en not_active Revoked
- 1992-02-19 EP EP92102740A patent/EP0501295B1/en not_active Revoked
- 1992-02-25 AU AU11229/92A patent/AU653984B2/en not_active Expired
- 1992-02-25 KR KR1019920002886A patent/KR920016632A/en not_active Application Discontinuation
- 1992-02-25 CA CA002061810A patent/CA2061810C/en not_active Expired - Lifetime
- 1992-02-25 JP JP4036820A patent/JPH0559632A/en active Pending
-
1995
- 1995-01-18 AU AU10261/95A patent/AU665918B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| KR920016632A (en) | 1992-09-25 |
| DE59207564D1 (en) | 1997-01-09 |
| AU1026195A (en) | 1995-03-16 |
| JPH0559632A (en) | 1993-03-09 |
| SG87724A1 (en) | 2002-04-16 |
| AU1122992A (en) | 1992-08-27 |
| ES2094833T3 (en) | 1997-02-01 |
| AU665918B2 (en) | 1996-01-18 |
| CA2061810A1 (en) | 1992-08-27 |
| EP0501295A1 (en) | 1992-09-02 |
| AU653984B2 (en) | 1994-10-20 |
| EP0501295B1 (en) | 1996-11-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5508073A (en) | Uncoated fabric for manufacturing air bags | |
| CA2061810C (en) | Uncoated fabric for manufacturing air bags | |
| CA2073957C (en) | Industrial fabrics of controlled air permeability and high ageing resistance and manufacture thereof | |
| KR960002057B1 (en) | Uncoated fabric for airbags | |
| US5881776A (en) | Rapier woven low permeability air bag fabric | |
| EP0682130B1 (en) | Air bag formed from water-jet woven fabric | |
| EP0639484B1 (en) | Filter cloth for air bag | |
| AU673227B2 (en) | Airbag and fabric for manufacturing same | |
| KR0173494B1 (en) | Polyester filament woven fabric for air bags | |
| US5637114A (en) | Fabric of high drapability, manufacture thereof, use thereof for making airbags, and airbag made thereof | |
| EP3279376B1 (en) | Polyester base fabric for airbag, polyester airbag, and method for manufacturing polyester base fabric for airbag | |
| JPH11507112A (en) | Airbag fabric | |
| EP3760775A1 (en) | Non-coated airbag base fabric, coated airbag base fabric, and airbag using same | |
| JPH04281062A (en) | Method for manufacture of closely woven, cover- free industrial textile and article consisting of said textile | |
| WO2024048153A1 (en) | Airbag fabric | |
| JP3849818B2 (en) | Airbag base fabric, airbag and method of manufacturing the same | |
| US20020155774A1 (en) | High density fabric for air bag and method for manufacturing high density fabric | |
| JP7188393B2 (en) | Airbag base fabric and airbag including the same | |
| JP4575633B2 (en) | Airbag fabric made from high denier yarn per filament | |
| EP3916139A1 (en) | Coated base fabric for airbag and airbag including same | |
| KR950008910B1 (en) | Air bag's fabric and it's making method | |
| EP1026049A1 (en) | Air bag | |
| JP3830332B2 (en) | Airbag base fabric and airbag | |
| JP4076593B2 (en) | Airbag base fabric and manufacturing method thereof | |
| KR100246517B1 (en) | Method of manufacturing nylon cloth for air bag |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |