WO2022196191A1

WO2022196191A1 - Non-coated textile for airbag

Info

Publication number: WO2022196191A1
Application number: PCT/JP2022/004926
Authority: WO
Inventors: 裕也清水; 啓令新開; 直樹川▲崎▼
Original assignee: 東レ株式会社
Priority date: 2021-03-16
Filing date: 2022-02-08
Publication date: 2022-09-22
Also published as: JPWO2022196191A1

Abstract

Provided is a non-coated textile for an airbag, the non-coated textile having low air permeability and high heat resistance, and being used for preventing damage to an airbag caused by high-temperature gas and residue during deployment of the airbag and reducing energy loss caused by permeation of air from an airbag body fabric portion. This non-coated textile for an airbag comprises synthetic fibers and is such that single fibers thereof are substantially round in cross-section, the non-coated textile being such that the melt drop time in a thermal resistance test in which an iron rod heated to 350°C is dropped into a base fabric is 1.1 seconds or greater, and the cover index A is 23,000 or greater.

Description

Non-coated fabric for airbags

The present invention relates to non-coated fabrics for airbags. More particularly, the present invention relates to a high-density non-coated airbag fabric having excellent heat resistance and low breathability.

Cars are equipped with airbags to ensure the safety of passengers. In the event of an automobile collision, the sensor activates upon receiving the impact of the collision and generates high-temperature, high-pressure gas inside the airbag. Protect the forehead.

In addition, in order to ensure higher safety for passengers, airbags are becoming larger with the aim of expanding the protection area, and the output of inflators is increasing accordingly. However, airbags
(a) In general, when the output of the inflator is increased, the temperature of the generated gas rises, and the base fabric used for the airbag main body melts due to heat when the airbag is deployed.
(b) In particular, the high-temperature residue (mainly copper) discharged from the inflator together with the blast adheres to the base fabric, causing melting and perforation starting from the adhered portion (speculation).
(c) Even if there is no residue, in the case of a highly air permeable base fabric, heat exchange is actively performed at the part where hot air leaks, so melt holes are likely to occur.
(d) In addition, in the case of a base fabric with high air permeability, energy loss is large and sufficient internal pressure cannot be secured.
Problems such as this also occur.

In order to solve the above problems, there have been conventionally proposed methods of applying a resin, film, or the like as a heat insulating layer to the fabric surface, as disclosed in Patent Documents 1 and 2. However, when such a method is used, the thickness of the woven fabric increases, and the compactness during storage deteriorates, which is disadvantageous as a woven fabric for airbags. In addition, there is a problem that the production cost of the airbag increases due to the increase in the resin application process and the film attachment process.

In addition, Patent Document 3 discloses a method of providing a fabric for airbags with improved heat resistance and instantaneous thermal deformation rate by adjusting the strength and elongation of polyethylene terephthalate fibers to produce polyethylene terephthalate fibers for airbags. Proposed. However, it is difficult to say that the airbag fabric of Patent Document 3 is of a level that can withstand high temperatures and high loads during deployment.

Japanese Patent Application Publication No. 2015-535502 Japanese Patent Publication No. 2015-508458 Japanese Patent Application Publication No. 2013-528719

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a non-coated fabric for airbags with low air permeability and high heat resistance.

A non-coated fabric for an airbag according to one aspect of the present invention that solves the above problems is a fabric made of synthetic fibers in which the single fibers have a substantially circular cross section, and has a heat resistance that causes an iron bar heated to 350 ° C. to drop onto the base fabric. The non-coated fabric for air bags has a test melt drop time of 1.1 seconds or more and a cover index X represented by the following formula (1) of 23000 or more.
Cover index X=d(Wp+Wf)×F ^1/2 (1)
d: single fiber diameter (μm), Wp: warp density (lines/2.54 cm), Wf: weft density (lines/2.54 cm), F: number of filaments

FIG. 1 is a schematic diagram for explaining the structure of weaving yarns forming the base portion of the fabric according to one embodiment of the present invention. FIG. 2 is a schematic diagram for explaining the structure of weaving yarns forming selvages of the fabric according to one embodiment of the present invention. FIG. 3 is a schematic diagram for explaining a method of measuring the aspect ratio of yarn.

[Non-coated fabric for airbags]
A non-coated woven fabric for an airbag (hereinafter also simply referred to as a woven fabric) of one embodiment of the present invention is a woven fabric made of synthetic fibers in which single fibers have a substantially circular cross section. The woven fabric has a melt drop time of 1.1 seconds or more in a thermal resistance test in which an iron bar heated to 350° C. is dropped onto the base fabric. The woven fabric has a cover index X of 23000 or more, which is represented by the following formula (1).
Cover index X=d(Wp+Wf)×F ^1/2 (1)
d: single fiber diameter (μm), Wp: warp density (lines/2.54 cm), Wf: weft density (lines/2.54 cm), F: number of filaments

The base portion of the woven fabric of the present embodiment is preferably made of synthetic fiber multifilament (hereinafter also referred to as synthetic fiber yarn). Here, the base portion means the portion of the woven fabric body other than the selvage portion. Synthetic fiber materials include, for example, polyamide-based fibers, polyester-based fibers, aramid-based fibers, rayon-based fibers, polysulfone-based fibers, ultra-high molecular weight polyethylene-based fibers, and the like.

Among synthetic fiber materials, polyamide-based fibers and polyester-based fibers, which are excellent in mass productivity and economic efficiency, are preferable.

Polyamide-based fibers include, for example, nylon 6, nylon 66, nylon 12, nylon 46, copolymer polyamide of nylon 6 and nylon 66, copolymer obtained by copolymerizing nylon 6 with polyalkylene glycol, dicarboxylic acid, amine, etc. It is a fiber made of polymerized polyamide or the like. Among these, polyamide-based fibers are preferably nylon 6 fibers and nylon 66 fibers because they are particularly excellent in strength.

Polyester fibers are, for example, fibers made of polyethylene terephthalate, polybutylene terephthalate, and the like. The polyester fiber may be a fiber made of a copolymer polyester obtained by copolymerizing polyethylene terephthalate or polybutylene terephthalate with isophthalic acid, 5-sodium sulfoisophthalic acid, or an aliphatic dicarboxylic acid such as adipic acid as an acid component. .

Synthetic fibers are treated with heat stabilizers, antioxidants, light stabilizers, smoothing agents, antistatic agents, plasticizers, thickeners, pigments, Additives such as flame retardants may also be included.

The cross-sectional shape of the synthetic fiber monofilament has a substantially circular cross section. As a result, the woven fabric of the present embodiment can obtain stable spinnability and high-order workability, and can be easily densified.

In the woven fabric of this embodiment, it is usually preferred that the same synthetic fiber yarn is used as warp and weft. The same synthetic fiber yarn is used for warp and weft means that both warp and weft are made of the same type of polymer, both warp and weft have the same single fiber fineness, and both warp and weft have the same total fineness. is. Polymers of the same type refer to polymers having a common main repeating unit, such as nylon 66 and polyethylene terephthalate. For example, a combination of a homopolymer and a copolymer is also preferably used as the same kind of polymer as used in the present embodiment. Furthermore, if the presence or absence of a copolymerization component and, if copolymerization is used, the type and amount of the copolymerization component are the same combination, then there is no need to distinguish between the warp and the weft, which is preferable from the standpoint of production management.

In this embodiment, it is preferable to use a synthetic fiber filament with a single fiber fineness of 1 to 7 dtex as the synthetic fiber thread used as the base thread of the fabric. By setting the single fiber fineness to 7 dtex or less, the voids occupied between the single fibers in the woven fabric are reduced, and the fiber filling effect is further improved. Therefore, the woven fabric is preferable because it can reduce the air permeability. In addition, when the single fiber fineness is small, the rigidity of the synthetic fiber filament is lowered, and the effect of improving the flexibility of the woven fabric is also obtained. Therefore, the obtained airbag has an improved storability, which is preferable.

The total fineness of the synthetic fiber thread used as the base thread of the fabric is preferably 450 dtex or more, more preferably 470 dtex or more. Further, the total fineness of the synthetic fiber yarn used as the base yarn of the woven fabric is preferably 950 dtex or less, more preferably 550 dtex or less, and even more preferably 500 dtex or less. By setting the total fineness of the synthetic fiber yarn used as the base yarn to 450 dtex or more, the woven fabric tends to maintain excellent heat resistance and strength. In addition, by setting the total fineness to 950 dtex or less, the obtained woven fabric tends to maintain excellent compactness and low air permeability when stored. When the total fineness is within the above range, the woven fabric can have well-balanced improvements in heat resistance, low air permeability, strength, slip resistance, flexibility, and compact storability.

The number of filaments is preferably 90-150. The number of filaments is preferably 90 or more. As a result, the single fibers of the woven fabric tend to have the closest-packed structure, and a low air-permeability base fabric with few voids between single fibers can be easily obtained. In addition, since the single fibers are thin and flexible, it is easy to obtain a woven fabric with excellent flexibility. Also, the number of filaments is preferably 150 or less. As a result, the single fiber strength of the woven fabric is increased, so that single fiber breakage in the spinning process and the weaving process is reduced, and stable spinning and weaving properties are easily obtained.

The tensile strength of the synthetic fibers (especially the synthetic fiber yarns used as base yarns) constituting the woven fabric of the present embodiment is preferably 8.0 cN/dtex or more, and is preferably 8.3 cN/dtex or more. more preferred. In addition, the tensile strength of the synthetic fibers constituting the woven fabric (especially the synthetic fiber yarn used as the base yarn) is preferably 9.0 cN/dtex or less, more preferably 8.7 cN/dtex or less. . When the tensile strength of the synthetic fibers that make up the fabric (especially the synthetic fiber yarn used as the base yarn) is within the above range, the fabric easily satisfies the mechanical properties required for an airbag, and the yarn manufacturing operation Excellent from all sides.

If the woven fabric produced in this embodiment is composed of warp and weft yarns made of the same synthetic fiber yarn as described above, the texture of the woven fabric is not particularly limited. Examples of the woven fabric include plain weave, twill weave, satin weave, variations of these weaves, multiaxial weave, and the like. Among these, the woven fabric is preferably plain weave because it has excellent mechanical properties, which are particularly necessary for airbag applications, and is thin.

The weave density can vary depending on whether the fabric is resin-treated or not, and also depending on the fineness of the weaving yarn. In this embodiment, it is important that the cover index X defined by the following formula (1) is 23,000 or more, and preferably 24,000 or more. If the cover index X is less than 23,000, the weaving yarns are insufficiently entwined in the woven fabric, and voids increase, making it difficult to ensure low air permeability. In addition, since the number of yarns per unit area of the woven fabric is reduced, the heat capacity of the woven fabric is reduced, making it difficult to ensure heat resistance. In formula (1), d is the single fiber diameter (μm), Wp is the warp density (line/2.54 cm), Wf is the weft density (line/2.54 cm), and F is the filament. is a number.
Cover index X=d(Wp+Wf)×F ^1/2 (1)

In addition, from the viewpoint of air permeability and heat resistance, the aspect ratio A of the threads (warp and weft) in the base portion of the fabric (calculated from the five-point average of the thickness and width of the threads using the formula (2)) is 3. It is preferably 0.0 or more. Also, the aspect ratio A is preferably 4.0 or less, more preferably 3.5 or less. When the aspect ratio A is 3.0 or more, the distance between adjacent warps or wefts in the woven fabric is reduced, the porosity is reduced, and the fabric becomes a low air permeability base fabric. When the aspect ratio A is 4.0 or less, the woven fabric has a three-dimensional surface, which reduces the contact surface with hot gas and residue, making it difficult for heat to melt and penetrate the woven fabric.

For thermal resistance, it is important that the melt drop time in a thermal resistance test called a hot rod test, in which an iron rod heated to 350°C is dropped onto the base fabric, is 1.1 seconds or longer, and 1.5 seconds or longer. is preferred. When the melting time is 1.1 seconds or longer, the fabric is less likely to melt due to the high temperature gas generated from the inflator and the residue during the deployment test, and to burst the airbag accordingly.

In addition, regarding the air permeability of the fabric, the dynamic air permeability measured based on ASTM D 6467 is preferably 300 mm/s or less, more preferably 290 mm/s or less. If the dynamic air permeability is within the above range, it is easy to obtain an airbag that is excellent in internal pressure retention with little energy loss during deployment of the airbag.

In general, when weaving fabrics for airbags, entwining yarns and additional yarns are used for the selvage ends. Furthermore, in some cases, ear tightening threads are used between the additional threads and the warp threads in order to reduce the ear lobes.

The "entanglement thread" is also called a leno, and in order to prevent the selvage from fraying, multiple threads are intertwined on the outermost side of the selvage of the fabric and tighten the weft threads to form selvages. When forming the ears, it is generally preferred to use a planetary gear mechanism, more preferably a planetary gear twist system. Other methods of forming the ears may be used. The material, type, and fineness of the entwining thread are appropriately selected according to the type of ground thread and weaving density. It is preferable that the number of wires to be used is two or more, more preferably two, at each end. Monofilament is generally used as the entwining thread because it has excellent selvage binding performance. A multifilament may be used as the leno yarn. The material of the entanglement thread is preferably the same as that of the ground thread. The fineness of the entwining yarn is preferably 33 dtex or less. If the fineness exceeds 33 dtex, the woven fabric may fray at the selvage. The fineness of the leno yarn is preferably 5 to 22 dtex.

"Additional threads" are used for the purpose of preventing fraying of the selvage of the fabric, similar to the entwining threads, and are placed between the entwining threads and the warp in the selvage of the fabric to assist the entwining threads. However, the planetary system is not used for additional yarns. The additional yarn is preferably used in a plain weave that is excellent in selvage tightening properties. Further, the material, type, and fineness of the additional yarn are appropriately selected according to the type of base yarn and the weaving density. As with the entwining yarn described above, the additional yarn is preferably a monofilament that has excellent selvage tightening performance. The number of additional yarns, if used, is, for example, 2 to 12 on each end. The fineness of the additional yarn is preferably 33 dtex or less. If the fineness exceeds 33 dtex, the woven fabric may fray at the selvage. The fineness of the leno yarn is preferably 5 to 22 dtex.

"Ear tightening thread" is sometimes used for the purpose of preventing the selvedge of the fabric, apart from the entanglement thread and the additional thread, and is placed between the additional thread and the warp in the selvage of the fabric. As with the increase yarn, no planetary system is used. The selvage tightening thread is preferably used in a plain weave that is excellent in selvage tightening properties. The material, type, and fineness of the ear tightening thread are appropriately selected according to the type of ground thread and weaving density. Multifilament having a total fineness of 80% or more with respect to the total fineness of the base threads is preferably used as the selvage thread for weaving under high tension. If the total fineness is less than 80% of the ground yarn, it will be difficult to weave the woven fabric with high tension, and it will be difficult to obtain the effect of preventing ear flaps. The number of ear tightening threads, if used, is for example 4 to 8 on each end.

The woven fabric of the present embodiment has weaving yarns YA and YB arranged in the warp direction with different crimp ratios in at least one selvage of the woven fabric, and YA and YB are repeatedly arranged, and the crimp of YA is It is preferable that the ratio CA and the crimp ratio CB of YB satisfy the relationship CA≧CB×1.2. In the present embodiment, the weaving yarns YA and YB having different crimp ratios and arranged in the warp direction are not limited to warp yarns (base yarns), entwining yarns, additional yarns, and ear tightening yarns. . The weaving yarns YA and YB are preferably warp yarns, additional yarns, or selvage yarns. The yarns YA and YB preferably have the same type of polymer or the same total fineness, but may have different polymers or total fineness.

The weaving yarns YA and YB arranged in the warp direction and having different crimp ratios are preferably arranged repeatedly in at least one selvage of the fabric. In general, the "selves" of a fabric refer to portions within 100 mm from the ends of the fabric. In this embodiment, the portion where the weaving yarns YA and YB are repeatedly arranged is preferably arranged within 25 mm from the selvage of the fabric. If the length exceeds 25 mm from the edge of the selvage, the selvage where the weaving yarns YA and YB are repeatedly arranged has different characteristics as a fabric from the base portion of the fabric, so that the portion that can be used for cutting as an airbag becomes smaller. loss may increase. The positions and widths of the weaving yarns YA and YB within 25 mm from the selvage are not particularly limited. In order to effectively suppress the receding of the texture and the occurrence of flaring before weaving during weaving, the weaving yarns YA and YB are repeatedly arranged with a width of 5 mm or more at a site of 1 to 15 mm from the edge of the selvage. is preferred.

In this embodiment, the crimp ratios CA and CB of the weaving yarns YA and YB preferably satisfy the relationship CA≧CB×1.2. The crimp ratios CA and CB of the weaving yarns YA and YB more preferably satisfy the relationship CA≧CB×2.0, and more preferably satisfy the relationship CA≧CB×3.0. As shown in FIG. 1, the base portion of the woven fabric in this embodiment includes weaving yarns YC arranged in the warp direction intersecting the weft yarns 10 and adjacent weaving yarns YC, as in a general plain weave fabric. , with the same crimp rate. If the weaving density can be increased at this time, the weft yarn driving limit will occur, and the receding of the weave will increase during weaving. On the other hand, as shown in FIG. 2, when the crimp ratios of YA and YB are different, the crimp structure of the selvedge portion of the woven fabric in the present embodiment is changed, and the selvedge portion of the woven fabric is different from that of the general plain weave fabric. can also make it easier to drive the weft. As a result, the fabric can be densified in weave density. By creating such a crimp structure in the selvage, it becomes easier for the weft to be driven into the selvage than in the base. As a result, it is possible to effectively suppress the receding of the cut edge and the occurrence of flare during weaving. In addition, if the woven fabric satisfies the relationship CA≧CB×1.2, a sufficient suppression effect due to the crimp structure change can be obtained.

In the present embodiment, YA and YB are preferably arranged adjacently to form a flat weave. By arranging YA and YB adjacently, the woven fabric can obtain a sufficient effect of densification due to the change in crimp structure. The method of arranging YA and YB is preferably, for example, a method of alternately arranging YA and YB (1:1). The method of arranging YA and YB is such that the ratio is changed such that the arrangement is 2:1 or 10:1, or the arrangement is appropriately selected such as 2:2 or 8:8. In this way, it is possible to obtain the effect of suppressing the receding of the weave and the occurrence of flare. As for the method of arranging YA and YB, it is particularly preferable to arrange YA and YB adjacent to each other at a ratio of 1:1 so that the arrangement is repeated, and a sufficient inhibitory effect can be easily obtained. The woven structure composed of YA and YB can obtain the effect of the present embodiment even when ridged structure is formed by aligning YA and YB, for example. It is particularly preferable that the weave structure composed of YA and YB is a plain weave that is excellent in selvage tightening properties.

In this embodiment, at least one of YA and YB is preferably made of the same synthetic fiber as the weaving yarn YC arranged in the warp direction constituting the base portion of the fabric. For example, if YA and YB are made of yarns having characteristics such as total fineness or shrinkage that are significantly different from those of YC, differences in the thickness and shrinkage characteristics of the woven fabric between the base portion and the selvage portion are likely to appear. Therefore, the woven fabric tends to wrinkle at the selvage when it is wound into a roll and in the subsequent scouring, setting and coating processes. If at least one of YA and YB is the same synthetic fiber as YC, the difference between the base portion and the selvage portion is reduced. Therefore, the woven fabric is preferable because the selvage is less likely to wrinkle. Moreover, it is particularly preferable that YA, YB, and YC are all made of the same synthetic fiber.

In this embodiment, the YC crimp rate CC preferably satisfies the relationship CA>CC>CB. By satisfying the relationship CA>CC>CB, it is easy to obtain a base portion having a woven structure as shown in FIG. 1 and a selvage portion having a woven structure as shown in FIG. As a result, in the woven fabric, the weft yarns in the selvage portion are denser than in the base portion, and the occurrence of flare can be effectively suppressed. When CA and CB are smaller than CC (CC>CA>CB), the crimp of the weaving yarn in the selvage portion is smaller than that in the base portion. Therefore, the woven fabric tends to have coarse and hard selvages, which may cause wrinkles. If CA and CB are larger than CC (CA>CB>CC), the woven fabric cannot obtain sufficient selvage tightening properties, and it is difficult to obtain the effect of suppressing the receding of the weave and the occurrence of flare.

[Manufacturing method of non-coated fabric for airbag]
A method for manufacturing an uncoated fabric for an airbag (hereinafter also simply referred to as a method for manufacturing a fabric) according to one embodiment of the present invention is the method for manufacturing an uncoated fabric for an airbag (airbag fabric) according to the present embodiment. . The fabric manufacturing method comprises weaving yarns YA and YB arranged in the warp direction with different crimp ratios in at least one selvage of the fabric with different tensions, and tensions TA and TB applied to YA and YB, respectively. is characterized by satisfying the relationship TB≧TA×1.2. Therefore, other steps shown below are all examples, and may be replaced with other known steps.

According to the manufacturing method of the present embodiment, first, the warp yarns having the total fineness described above in relation to the woven fabric are warped and installed on the loom. Similarly, the weft threads are placed on the loom. A loom is not particularly limited. It is preferable to use a loom equipped with a full-width temple device when weaving high-density fabrics. Examples of looms include water jet looms, air jet looms, rapier looms, and the like. Among these, a water jet loom is preferable as the loom because high-speed weaving is relatively easy and productivity can be easily improved.

During weaving, it is preferable that the tension applied to each warp constituting the base portion of the fabric is adjusted in the range of 0.2 to 0.5 cN/dtex. When the warp tension is within the above range, the dimensional stability of the resulting woven fabric can be improved by reducing the inter-filament voids in the bundle of multifilament yarns constituting the woven fabric. If the warp tension is less than 0.2 cN/dtex, the binding force of the weft yarn during weaving is low, and it is difficult to obtain a fabric having the same density between the warp yarn and the weft yarn. On the other hand, when the warp tension exceeds 0.5 cN/dtex, the contact area (adhesion) between the warp and the weft tends to increase in the woven fabric. Therefore, the warp tends to become fuzzy, and the weaving properties tend to deteriorate. A method for adjusting the average warp tension is not particularly limited. For example, the average warp tension can be adjusted by a method of adjusting the warp let-off speed of the loom, a method of adjusting the weft driving density, or the like. Whether or not the average warp tension is within the above range can be confirmed, for example, by measuring the tension applied to each warp between the warp beam and the central portion of the back roller during operation of the loom with a tension measuring instrument.

Also, in order to optimize the aspect ratio obtained by dividing the width of the cross section of the yarn in the width direction central portion of the fabric by the thickness, it is preferable to adjust the easing timing and the opening amount of the warp heald frame. When weaving a high-density fabric, a sharp increase in tension occurs at the timing of beating due to the retraction of the weave opening before weaving. As a result, the aspect ratio of the warp yarns increases, resulting in a smooth base fabric and reduced heat resistance. In addition, a rapid increase in warp tension causes yarn breakage and fluff. In view of the above problems, it is preferable to minimize the shedding angle, specifically to set the shedding angle to 24° or less, in order to suppress the tension increase at the time of warp shedding. In addition, although it depends on the weaving density, in order to suppress the increase in tension during beating, the easing timing is delayed from the beating timing, specifically by 310°, while considering the tension peak at the time of shedding. It is preferable to adjust the angle to 340° or less.

In the fabric manufacturing method of the present embodiment, weaving yarns YA and YB arranged in the warp direction with different crimp ratios are woven with different tensions in at least one selvage of a fabric woven by a loom. Each tension TA, TB applied to YB is characterized by satisfying the relationship TB≧TA×1.2. The weaving yarns YA and YB arranged in the warp direction and having different crimp ratios are not limited to warp yarns, entanglement yarns, additional yarns, and selvage tightening yarns. The weaving yarns YA and YB are preferably warp yarns, additional yarns, or selvage yarns. The yarns YA and YB are preferably of the same kind of polymer or have the same total fineness. Yarns YA, YB may be of different polymers or total fineness.

The weaving yarns YA and YB arranged in the warp direction and having different crimp ratios are preferably arranged repeatedly in at least one selvage of the fabric. In this embodiment, the portion where the weaving yarns YA and YB are repeatedly arranged is preferably arranged within 25 mm from the selvage of the fabric. If the length exceeds 25 mm from the edge of the selvage, the number of weaving yarns YA and YB in the woven fabric increases, making it difficult to thread the yarn and manage the tension. The position and width of the weaving yarns YA and YB within 25 mm from the edge of the selvage are not particularly limited. It is preferable that the weaving yarns YA and YB are repeatedly arranged with a width of 5 mm or more at a portion of 1 to 15 mm from the selvage.

In the fabric manufacturing method of the present embodiment, it is important that the respective tensions TA and TB applied to the weaving yarns YA and YB satisfy the relationship TB≧TA×1.2. Moreover, the tensions TA and TB preferably satisfy the relationship TB≧TA×1.5, and more preferably satisfy the relationship TB≧TA×2.0. In general, when the tension applied to the weaving yarn is increased during weaving, the crimp rate of the weaving yarn decreases. On the other hand, when the tension applied to the yarn during weaving is reduced, the crimp rate of the yarn increases. By increasing the difference between the respective tensions TA and TB applied to YA and YB, the difference in crimp rate is increased, and the change in crimp structure makes it easier to obtain the effect of increasing the weaving density. As a result, the fabric manufacturing method can effectively suppress the receding of the weave before weaving and the occurrence of flare during weaving. A method for adjusting the respective tensions TA and TB applied to the weaving yarns YA and YB is not particularly limited. For example, the tensions TA and TB can be adjusted by supplying weaving yarns one by one from a paper tube or bobbin and managing the tension with a tensor such as a spring washer. It can be adjusted by a method of preparing a beam for the warp yarn, a method of changing the tension for winding only the selvage yarn when the warp beam is warped, and the like. The ranges of the respective tensions TA and TB applied to the weaving yarns YA and YB are not particularly limited. The tensions TA and TB are preferably adjusted in the range of 0.1 to 0.6 cN/dtex.

In the fabric manufacturing method of the present embodiment, it is preferable to form a plain weave by arranging YA and YB adjacent to each other. By arranging YA and YB adjacent to each other, the resulting woven fabric can exhibit a sufficient effect of increasing the density due to the change in crimp structure. The method of arranging YA and YB is preferably, for example, a method of alternately arranging YA and YB (1:1). The method of arranging YA and YB is such that the ratio is changed such that the arrangement is 2:1 or 10:1, or the arrangement is appropriately selected such as 2:2 or 8:8. In this way, it is possible to obtain the effect of suppressing the receding of the weave and the occurrence of flare. As for the method of arranging YA and YB, it is particularly preferable to arrange YA and YB adjacent to each other at a ratio of 1:1 so that the arrangement is repeated, and a sufficient inhibitory effect can be easily obtained. The woven structure composed of YA and YB can obtain the effects of the present embodiment even when the ridge structure is formed by aligning YA and YB, for example. The woven weave is particularly preferably a plain weave that is excellent in selvage tightening properties.

In the fabric manufacturing method of the present embodiment, at least one of YA and YB is preferably made of the same synthetic fiber as the weaving yarn YC arranged in the warp direction constituting the base of the fabric. For example, if YA and YB are made of yarns with characteristics such as total fineness or shrinkage that are significantly different from those of YC, the obtained fabric tends to show differences in thickness and shrinkage characteristics as a fabric between the base portion and the selvage portion. Therefore, the woven fabric obtained is likely to have wrinkles at the selvages when the woven fabric is wound into a roll and in the subsequent scouring, setting and coating processes. If at least one of YA and YB is the same synthetic fiber as YC, the difference between the base portion and the selvage portion is reduced. Therefore, the woven fabric is preferable because the selvage is less likely to wrinkle. Moreover, it is particularly preferable that YA, YB, and YC are all made of the same synthetic fiber.

In the fabric manufacturing method of the present embodiment, the tension TC applied to YC preferably satisfies the relationship TB>TC>TA. By satisfying the relationship TB>TC>TA, it is easy to obtain the base portion having the woven structure as shown in FIG. 1 and the selvage portion having the woven structure as shown in FIG. As a result, the resulting woven fabric is more likely to be driven by the weft in the selvage than in the base. As a result, the woven fabric can effectively suppress the receding of the weave before weaving and the occurrence of flare during weaving. When TA and TB are larger than TC (TB>TA>TC), the crimp of the weaving yarn in the selvage portion is smaller than that in the base portion. Therefore, the woven fabric tends to have coarse and hard selvages, which may cause wrinkles. In addition, when excessive tension is applied only to the edge of the selvage during weaving, the selvage of the woven fabric may collapse. If TA and TB are larger than TC (TA > TB > TC), the woven fabric cannot obtain sufficient selvage tightening properties, and it becomes difficult to obtain the effect of suppressing the receding of the texture and the occurrence of flare. .

After the weaving is finished, the resulting fabric is dried if necessary. The drying temperature is usually 80° C. or higher. When the drying temperature is 80° C. or higher, the woven fabric has a small dry heat shrinkage and improved dimensional stability. As a result, the woven fabric can be suitably used as an airbag.

Next, the fabric is appropriately subjected to processing such as scouring and heat setting. The scouring temperature in the scouring process is preferably 20° C. or higher, more preferably 25° C. or higher. Also, the scouring temperature is preferably 90° C. or lower, more preferably 80° C. or lower. If the scouring temperature is 20° C. or higher, the fabric may be freed of residual strain and the dimensional stability of the fabric may be improved. As such, the fabric may have improved dimensional stability. Further, when the scouring temperature is 80° C. or less, excessive shrinkage of the fabric is suppressed. As a result, in the woven fabric, the threads spread flatly with respect to the woven fabric, and the low breathability can be improved.

As with scouring, the heat setting temperature in heat setting is preferably a temperature that can remove residual strain in the woven fabric after weaving and can suppress large shrinkage of the multifilament yarn. Specifically, the heat setting temperature is preferably 110° C. or higher, more preferably 120° C. or higher. Also, the heat setting temperature is preferably 180° C. or lower. It is more preferably 170° C. or less. When the heat-setting temperature is within the above range, the obtained woven fabric can be prevented from heat damage and excessive shrinkage, and can be improved in low air permeability.

The woven fabric that has undergone the above processes may be subjected to selvage cutting as appropriate. The woven fabric of the present embodiment is subjected to selvage cuts, thereby facilitating position adjustment at the time of cutting. The portions of the fabric to be discarded in the selvage cutting are cut from the selvage of the fabric to the entwining thread, additional yarn, selvage tightening thread, and the warp up to about 25 mm from the selvage where the pin hole is made by heat setting. By cutting the portion of the selvage that is not used as the woven fabric, the woven fabric manufacturing method can increase the number of sheets that can be laminated in the cutting process, and the cutting efficiency can be improved.

As described above, according to the manufacturing method of the present embodiment, it is possible to suppress the receding of the weave opening at the edge of the selvage during weaving of the non-coated fabric for airbags, and the non-coated fabric for airbags with high density, low breathability, and excellent storability. Textiles can be provided.

An embodiment of the present invention has been described above. The present invention is not particularly limited to the above embodiments. It should be noted that the above-described embodiment mainly describes an invention having the following configuration.

(1) A woven fabric made of synthetic fibers whose monofilaments have a substantially round cross section, and in a thermal resistance test in which an iron bar heated to 350 ° C. is dropped onto the base fabric, the melt drop time is 1.1 seconds or more, A non-coated fabric for airbags, wherein the cover index X represented by the following formula (1) is 23000 or more.
Cover index X=d(Wp+Wf)×F ^1/2 (1)
d: single fiber diameter (μm), Wp: warp density (lines/2.54 cm), Wf: weft density (lines/2.54 cm), F: number of filaments

(2) The non-coated fabric for airbags according to (1), wherein the aspect ratio A of the warp and weft yarns in the base portion of the fabric represented by the following formula (2) is 3.0 to 4.0. .

(3) having weaving yarns YA and YB arranged in the warp direction with different crimp ratios in at least one selvage of the fabric;
YA and YB are arranged repeatedly,
The non-coated fabric for airbags according to (1) or (2), wherein the crimp rate CA of YA and the crimp rate CB of YB satisfy the relationship CA≧CB×1.2.

(4) The non-coated fabric for airbags according to any one of (1) to (3), which has a dynamic air permeability of 300 mm/s or less as measured according to ASTM D 6467.

(5) The non-coated fabric for airbags according to any one of (1) to (4), wherein the number of filaments of the constituent yarn is 90 to 150.

(6) The non-coated fabric for airbags according to any one of (1) to (5), wherein the total fineness of the constituent threads is 450 to 950 dtex.

The present invention will be specifically described below with reference to examples. The present invention is by no means limited to these examples. In addition, in the following examples, each characteristic value was calculated by the following method.

<Method for calculating characteristic values>
(total fineness)
The total fineness D was calculated according to JIS L 1013:2010 8.3.1 A method by measuring the regular fineness with a predetermined load of 0.045 cN/dtex.

(number of filaments)
The number of filaments was calculated based on the method of JIS L 1013:2010 8.4.

(single fiber diameter)
The single fiber diameter d (μm) was calculated from the following formula (3).

D: total fineness (dtex), f: number of filaments, ρ: polymer specific gravity (g/m ³ ).

(weave density)
The weave density of each warp and weft was calculated based on JIS L 1096:2010 8.6.1. Specifically, the sample was placed on a flat table, unnatural wrinkles and tension were removed, and the number of warp and weft yarns in a 2.54 cm section was counted at five different locations, and the average value of each was calculated.

(cover index)
The cover index X was calculated by the following formula (1).
X=d(Wp+Wf)×F ^1/2 (1)
d: single fiber diameter (μm), Wp: warp density (lines/2.54 cm), Wf: weft density (lines/2.54 cm), F: number of filaments

(Yarn aspect ratio)
The warp 12 or the center 13 of the weft 12 of the woven fabric is cut in the thickness direction, the cut surface is observed with an SEM photograph, and the warp arranged above and below the weft of the cut cross section, or above and below the warp of the cut cross section Five (10 in total) weft cross sections and warp cross sections 11 were selected at random for the arranged wefts, and in each cross section, single fibers in the fabric thickness direction and width direction (direction perpendicular to the thickness direction) were measured. The spread (a and b) is measured, the values obtained by averaging five points are set as a _p , a _f , b _p , and b _f , and the aspect ratio A of the yarn in the woven fabric is obtained using the formula (2). (See Figure 3).

(Melting drop time in thermal resistance test)
After cutting test pieces of 150 mm×150 mm along the warp and weft at five different locations on the woven fabric, the test pieces were attached to a hot rod tester (manufactured by MEGA SCIENCE). In addition, a hot rod (steel material, diameter 10 mm, length 82 mm, weight 50 g, thermal conductivity 55 W / m K) was heated at 350 ° C. for 1 hour with the above device, and the test piece was separated from the test piece by a distance of 100 mm. The hot rod was placed in the upward direction of the piece and allowed to freely fall to the side of the specimen at said position. From the moment the free-falling hot rod starts free-falling, measure the time t a from when the test piece completely passes through to when it touches the bottom of the pan, and then measure the time t _a when the test piece is not installed. The average value of Δt minus the drop time t _b of the bar at 100° C. was calculated as the melt drop time in the thermal resistance test.

(dynamic air permeability)
In accordance with ASTM D 6476-02, using the airbag air permeability tester FX3350 manufactured by TEXTEST, using a test head of 400 cm3, the pressure of compressed air (START PRESSURE) filled in the test head is the maximum applied to the fabric. The pressure was adjusted to 100±5 kPa, the compressed air filled in the test head was released and applied to the fabric sample, and the pressure and air permeability were measured over time. Measurements were taken at 6 different locations on the sample. The average flow velocity (mm/sec) within the range from the upper limit pressure (UPPER LIMIT: 70 kPa) to the lower limit pressure (LOWER LIMIT: 30 kPa) after reaching the maximum pressure in the pressure-dynamic air permeability curve obtained as a result of the measurement is obtained, The average value was determined as the dynamic air permeability (mm/sec).

(Texture contact timing)
A series of periodic movements of the loom, in which the reed moves backward from the forefront position, the weft thread is inserted into the open warp threads, and the reed moves forward to drive the weft thread, is represented by the rotation angle of the loom from 0° to 360°. With the reed being at the foremost position as the rotation angle of 0°, the rotation angle at the moment when the reed touches the weft when the reed drives the weft yarn was measured and used as the weave contact timing. The weave contact timing is measured by applying a timing light for the loom while the loom is operating and weaving the fabric, and the ground part in the center of the fabric and the weft supply side / anti-yarn supply side are measured. Each selvage was measured, and the selvage was calculated as the average value of the yarn feeding side and the non-yarn feeding side. For the evaluation of weave receding, the difference between the ground part and the selvage is judged as the size of the weave receding. was "B", and 8° or more was "C".

(Presence or absence of ear lobes in fabric)
Cut the woven fabric to a length of 1 m and spread it on a flat desk, measure the height of the most raised part of the selvage in 1 mm increments (round off amounts less than 1 mm), and average both selvages value was calculated. In the evaluation, the height of the earlobe was judged as the size, and less than 8 mm was evaluated as "S", 8 mm or more and less than 10 mm as "A", 10 mm or more and less than 12 mm as "B", and 12 mm or more as "C". Also, the woven fabric in which selvedge occurred was rated as "-".

(deployment test)
A module was assembled using an airbag for the driver's seat, a pyrotype inflator (output 190 kpa), a pressure gauge, an amplifier, and a fixing bracket. A deployment test was conducted under an environment of 25° C., and the opening of the sewn part during deployment, the presence or absence of burst, and the peak internal pressure were observed. The evaluation is based on the presence or absence of eye opening/burst and the peak internal pressure. An internal pressure of less than 50 kPa was rated as "B", and a burst was rated as "C". The airbag for the driver's seat was made as follows.

Two circular body panels with an outer diameter of φ640 mm and three circular reinforcing fabric panels with an outer diameter of φ240 mm were collected from the prepared uncoated airbag fabric. A φ76 mm inflator mounting port is provided at the center of the main body panel and the reinforcing fabric panel.

After that, three reinforcing fabric panels and one main body panel were overlapped and sewn in a circular shape at φ85 mm, φ180 mm, and φ196 mm from the center of the mounting opening with lockstitching at a pitch of 2.5 mm. After that, another main body panel is superimposed on the above four panels so that the warp direction is shifted by 45 degrees, and the position of φ615mm from the center of the installation opening is double chain stitched with a pitch of 2.5mm. and sewed in a circular shape.

After making the necessary bolt holes in the resulting bag to fix it to the fixing bracket, the bag was turned over so that the reinforcing fabric was on the inside, making it an airbag for the driver's seat.

<Example 1>
(warp, weft)
The warp and weft are made of nylon 66, have a circular cross-sectional shape, are composed of 136 single filaments with a single fiber fineness of 3.5 dtex, a total fineness of 470 dtex, and a tensile strength of 8.5 cN/dtex. A non-twisted synthetic fiber filament having an elongation of 23.5% was prepared.

(weaving)
Using the above yarn as the base yarn for the warp and weft, using a water jet loom equipped with a full-width temple, a plain weave with a warp weaving density of 57 / 2.54 cm and a weft weaving density of 57 / 2.54 cm. woven. At that time, the warp tension was adjusted to 0.4 cN/dtex. The weaving was carried out with the easing timing set at 330° and the warp shedding angle set at 24°.

At that time, entwining threads, additional threads, and ear tightening threads were used for both ears of the fabric. The leno yarn used was a 22 detex nylon 66 monofilament, two on each ear, fed from a planetary system. As the additional yarn, a 22 dtex nylon 66 monofilament similar to the leno yarn was used, and 8 yarns were supplied to each selvage from a bobbin. As the selvage tightening threads, the same 470 dtex untwisted synthetic fiber filaments as the warp constituting the base were used, and 24 filaments were used for each of the selvages. For the selvage tightening yarn, in order to control the tension at the time of supply, two beams on which 12 selvage tightening yarns were wound were prepared for each selvage, and the tension was adjusted by adjusting the supply speed of the warp yarn. The beam for supplying the selvage tightening thread is prepared with a low tension beam with a supply tension of 0.20 cN/dtex and a high tension beam with a supply tension of 0.50 cN/dtex. Low tension (YA) and high tension (YB) yarns were alternately arranged in a 1:1 ratio for weaving. The tension of the warp yarns (YC) forming the base portion was 0.40 cN/dtex.

In weaving, we were able to keep the receding back of the weave at the selvage to a minimum. YA with a crimp rate CA of 12% and YB with a crimp rate CB of 4% are repeatedly arranged in the selvage portion of the obtained fabric, and the crimp rate of YC constituting the ground portion is 10%. The woven fabric thus obtained had a small selvage, and the selvage tightness was uniform and good.

(scouring and heat setting)
Then, the resulting fabric was scoured at 80°C with an open soap scouring machine, washed with hot water at 40°C, and dried at 120°C. Further, using a pin tenter dryer, the width ratio was set so that the width was 50 mm narrower than the width of the fabric after drying, and the fabric was heat set at 160° C. for 60 seconds. Table 1 shows the properties of the resulting fabric.

(deployment test)
Next, the obtained woven fabric was sewn, an airbag was produced, and a deployment test was conducted on the airbag.

In the deployment test, the internal pressure retention was high, and the burst resistance was also very good.

<Example 2>
A non-coated fabric for an airbag was produced in the same manner as in Example 1, except that the weave density of both warp and weft was changed to 55 threads/2.54 cm.

In weaving, we were able to keep the receding back of the weave at the selvage to a minimum. In the selvage portion of the obtained fabric, YA with a crimp rate CA of 11% and YB with a crimp rate CB of 5% were repeatedly arranged at a ratio of 1:1. The crimp rate of the fabric was 9%, and the obtained woven fabric had small selvage, uniform and good selvage tightness, and was very good in both internal pressure retention and burst resistance in the airbag deployment test. . Table 1 shows the properties of the resulting fabric.

<Example 3>
A non-coated fabric for an airbag was produced in the same manner as in Example 1, except that the weave density of both warp and weft was changed to 53 threads/2.54 cm.

In weaving, we were able to keep the receding back of the weave at the selvage to a minimum. In the selvage portion of the obtained fabric, YA with a crimp rate CA of 10% and YB with a crimp rate CB of 4% were repeatedly arranged at a ratio of 1:1. The crimp rate CC was 8%, and the resulting fabric had a small selvage, uniform and good selvage tightness, and also had good internal pressure retention and burst resistance in an airbag deployment test. Table 1 shows the properties of the resulting fabric.

<Example 4>
A non-coated fabric for an air bag was woven in the same manner as in Example 1, except that polyethylene terephthalate yarn with a total fineness of 470 dtex and a filament number of 96 was used as the warp and weft for the base portion and selvage portion, respectively. The crimp rate of YC forming the ground portion was 11%. In weaving, we were able to suppress the receding of the weave opening of the selvage. In the selvage portion of the obtained fabric, YA with a crimp rate CA of 11% and YB with a crimp rate CB of 5% were repeatedly arranged at a ratio of 1:1. The crimp rate CC was 9%. Table 1 shows the properties of the resulting fabric. In the airbag deployment test, both internal pressure retention and burst resistance were good. Table 1 shows the properties of the resulting fabric.

<Example 5>
A non-coated fabric for an airbag was produced in the same manner as in Example 1, except that the easing timing was changed to 350°, the warp shedding angle was changed to 26°, the refining temperature was changed to 65°C, and the heat setting temperature was changed to 180°C.

In weaving, we were able to keep the receding back of the weave at the selvage to a minimum. In the selvage portion of the obtained fabric, YA with a crimp rate CA of 10% and YB with a crimp rate CB of 5% were repeatedly arranged at a ratio of 1:1. The crimp rate of the fabric was 8%, and the resulting woven fabric had small selvages and uniform and good selvage tightness. In the airbag deployment test, the internal pressure retention was slightly inferior, but the burst resistance was good. Table 1 shows the properties of the resulting fabric.

<Comparative Example 1>
A non-coated fabric for an airbag was produced in the same manner as in Example 1, except that the weaving density of both warp and weft was changed to 46 yarns/2.54 cm, and the ear tightening yarn was not used. However, it cannot be used as a non-coated fabric for airbags because of its low heat resistance, high dynamic air permeability and poor internal pressure retention. Table 1 shows the properties of the resulting fabric.

<Comparative Example 2>
Nylon 66 yarn with a total fineness of 210 dtex and 72 filaments was used as warp and weft for the base and selvage, respectively, and the weaving density of both warp and weft was changed to 77 / 2.54 cm. A non-coated fabric for an airbag was produced in the same manner as in Example 1. In weaving, we were able to suppress the receding of the weave opening of the selvage. In the selvage portion of the obtained fabric, YA with a crimp rate CA of 10% and YB with a crimp rate CB of 6% were repeatedly arranged at a ratio of 1:1. The crimp rate of the fabric was 8%, and the resulting woven fabric had small selvages and uniform and good selvage tightness. However, it cannot be used as a non-coated fabric for airbags because of its low heat resistance, high dynamic air permeability and poor internal pressure retention. Table 1 shows the properties of the resulting fabric.

As shown in Table 1, the non-coated fabrics for airbags obtained in Examples 1 to 5 were able to suppress the receding of the weave opening of the selvage to a small extent, so that the selvage of the obtained fabrics was small. The tightness of the ears was uniform and good.

On the other hand, the non-coated fabrics for airbags obtained in Comparative Examples 1 and 2 caused opening and bursting when the airbag was deployed, and could not be used as an airbag.

10 Weft yarn YC Weaving yarn YC arranged in the warp direction constituting the base of the fabric
YA Weaving yarn YA arranged in the warp direction constituting the selvage of the fabric
YB Weaving yarn YB arranged in the warp direction constituting the selvage of the fabric
a Warp or weft single fiber spread in the fabric thickness direction b Single warp or weft spread in the fabric width direction 11 Warp or weft 12 Warp or weft 13 Center of warp or weft

Claims

A woven fabric made of synthetic fibers in which the single fibers have a substantially circular cross section,
In a thermal resistance test in which an iron bar heated to 350 ° C. is dropped onto the base fabric, the melting drop time is 1.1 seconds or more,
A non-coated fabric for airbags, wherein the cover index X represented by the following formula (1) is 23000 or more.
Cover index X=d(Wp+Wf)×F 1/2 (1)
d: single fiber diameter (μm), Wp: warp density (lines/2.54 cm), Wf: weft density (lines/2.54 cm), F: number of filaments
2. The non-coated fabric for an airbag according to claim 1, wherein the aspect ratio A between the warp and the weft in the base portion of the fabric represented by the following formula (2) is 3.0 to 4.0.
At least one selvage of the fabric has weaving yarns YA and YB arranged in the warp direction with different crimp ratios,
YA and YB are arranged repeatedly,
3. The non-coated fabric for an airbag according to claim 1, wherein the crimp rate CA of YA and the crimp rate CB of YB satisfy the relationship CA≧CB×1.2.
The non-coated fabric for airbags according to any one of claims 1 to 3, which has a dynamic air permeability of 300 mm/s or less as measured according to ASTM D 6467.
The non-coated fabric for airbags according to any one of claims 1 to 4, wherein the number of filaments of the constituent threads is 90 to 150.
The non-coated fabric for airbags according to any one of claims 1 to 5, wherein the total fineness of the constituent threads is 450 to 950 dtex.