JP2010111958A - Non-coated woven fabric for air bags - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-coated woven fabric for air bags, which can keep an excellent low gas permeability required for woven fabrics for the air bags, and the low gas permeability also after an environmental aging test. <P>SOLUTION: There is provided the non-coated woven fabric for air bags, includes synthetic filament yarns having a total fineness of 200 to 700 dtex and a single filament fineness of 1 to 2 dtex, wherein the initial gas permeability of the woven fabric is not more than 0.50 L/cm<SP>2</SP>/min, when measured at a test differential pressure of 19.6 kPa, and the gas permeability after the woven fabric is subjected to a thermal aging treatment for 400 hrs in an environment of 120°C is not more than 150% based on the initial gas permeability. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-coated airbag fabric.

  In recent years, with the improvement of traffic safety awareness, the effectiveness of various airbags has been recognized as a result of the development of various airbags in order to ensure the safety of passengers in the event of a car accident. It is out.

  The airbag is inflated and deployed in the vehicle in a very short time after the vehicle has collided, thereby receiving the occupant moving by the reaction of the collision and absorbing the impact to protect the occupant. In view of this action, it is required that the air flow rate of the fabric constituting the airbag is small (low air permeability). In addition, the fabrics that make up airbags are required to maintain low air permeability at all times for a long period of time when they are used in automobiles. It is necessary to maintain a low air permeability without being influenced by.

  Conventionally, as a means for reducing the air flow rate of a fabric, a coated fabric in which a resin is applied to the fabric or a film is attached has been proposed.

  However, when a resin is applied or a film is applied, the thickness of the woven fabric increases and the compactness at the time of storage deteriorates, which is inappropriate as a woven fabric for an airbag. Moreover, there is a problem that the manufacturing cost increases due to the increase in the resin coating process and the film attaching process.

Therefore, in order to solve such problems, in recent years, non-coated fabrics have been proposed that reduce the air flow rate of fabrics by weaving synthetic filament yarns such as polyamide fibers and polyester fibers at high density without applying resin processing. For example, as a non-coated fabric realizing low air permeability, a non-coated air bag fabric excellent in low air permeability in which a drying finishing process is performed in multiple stages is disclosed (for example, see Patent Document 1). Although the document describes that low air permeability is possible in the initial stage and after the environmental aging test, among the fabrics described in the examples, the lowest air permeability is measured under a test differential pressure of 125 Pa. 0.10 cc / cm ² / sec, which corresponds to about 0.7 L / cm ² / min when measured under a test differential pressure of 19.6 kPa, and could not be said to have a low air permeability. . Further, the air permeability after the environmental aging test was about 180% higher than the initial air permeability, and it was difficult to say that low air permeability was obtained even after the environmental aging test.

Further, as a method for solving the heat aging resistance required for an airbag base fabric that is equipped in an automobile for a long period of time, an airbag base fabric made of a polycapramide fiber containing a copper compound is disclosed (for example, Patent Documents). 2). However, although in the literature with the lowest 6cc / cm ² /sec(=0.36L/cm ² / min as air permeability of the fabric), the air permeability after forced heat treatment ^{10cc / cm 2 / sec (=} 0 .60 L / cm ² / min), and the rate of change was 167%, and it was difficult to say that it had low air permeability that was never influenced by the environment.

Thus, the prior art has not realized a non-coated airbag fabric that can provide low air permeability even after the initial and environmental aging tests.
JP 2002-146646 A (Table 1) JP 2006-183205 A (Table 1)

  An object of the present invention is to provide a non-coated airbag fabric that can solve the above-described problems of the prior art and maintain low air permeability even after an environmental aging test.

That is, the present invention is a fabric for an airbag comprising a synthetic fiber multifilament yarn having a total fineness of 200 to 700 dtex and a single fiber fineness of 1 to 2 dtex, and the initial air permeability of the fabric is a test differential pressure of 19.6 kPa. When measured, the air permeability is 0.5 L / cm ² / min or less, and the air permeability after the fabric is subjected to heat aging treatment in an environment of 120 ° C. for 400 hours is 150% or less with respect to the initial air permeability. This is a non-coated airbag fabric.

  According to the present invention, it is possible to obtain a non-coated airbag fabric that has excellent low air permeability and maintains excellent low air permeability even after being installed in an automobile for a long time.

  The non-coated airbag fabric of the present invention is made of synthetic fiber multifilament yarn. For example, polyamide fibers, polyester fibers, aramid fibers, rayon fibers, polysulfone fibers, ultrahigh molecular weight polyethylene fibers, and the like can be used as the raw material for the synthetic fibers constituting the multifilament yarn. Of these, polyamide fibers and polyester fibers excellent in mass productivity and economy are preferable, and polyamide fibers are more preferable from the viewpoint of heat resistance and fluff.

  Examples of polyamide fibers include nylon 6, nylon 66, nylon 12, nylon 46, copolymer polyamide of nylon 6 and nylon 66, and copolymer obtained by copolymerizing nylon 6 with polyalkylene glycol, dicarboxylic acid, amine, and the like. Mention may be made of fibers made of polyamide or the like. Among these, nylon 6 fiber and nylon 66 fiber are particularly excellent in impact resistance and are preferable.

  Examples of the polyester fiber include fibers made of polyethylene terephthalate, polybutylene terephthalate, and the like. It may be a fiber made of a copolymerized polyester obtained by copolymerizing polyethylene terephthalate or polybutylene terephthalate with an aliphatic dicarboxylic acid such as isophthalic acid, 5-sodium sulfoisophthalic acid or adipic acid as an acid component.

  Synthetic fibers also have thermal stabilizers, antioxidants, light stabilizers, smoothing agents, antistatic agents, plasticizers, thickeners to improve productivity and properties in the spinning / drawing process and processing process. Additives such as additives, pigments, and flame retardants may be included.

  In addition, the cross-sectional shape of the single fiber of the synthetic fiber is not particularly limited, and other than a circular shape, a non-circular shape such as a Y shape, a V shape, a flat shape, and a hollow portion can also be used. .

  The total fineness of the synthetic fiber multifilament yarn constituting the non-coated airbag fabric of the present invention needs to be 200 to 700 dtex. When the total fineness is less than 200 dtex, the strength side of the fabric is lowered and low air permeability is hardly obtained. In addition, since it is difficult to stably obtain high-strength fibers, the quality of the fabric also deteriorates, and the productivity of both the raw yarn and the fabric deteriorates. On the other hand, if it exceeds 700 dtex, the number of single fiber yarns is too large to be composed of synthetic fibers having a single fiber fineness of 1 to 2 dtex, and it is extremely difficult to spin at a time. It becomes necessary to form them by combining yarns, which impairs productivity and makes it difficult to store the airbag in a compact manner. A preferable range of the total fineness is 230 to 500 dtex, and more preferably 280 to 470 dtex. By setting the total fineness within this range, the strength, low air permeability, and bag storage compactness of the base fabric can be improved in a balanced manner.

  The single fiber fineness of the synthetic fiber multifilament yarn used in the present invention needs to be 1 to 2 dtex, and preferably 1.2 to 1.8 dtex. By setting the single fiber fineness within this range, the multifilament yarn constituting the fabric has a finely packed structure, and not only the initial low air permeability can be obtained, but also the densely packed structure is maintained after the environmental aging resistance test. Therefore, low air permeability can be maintained. When the single fiber fineness is less than 1 dtex, it is preferable in terms of low air permeability, but the spinnability is extremely lowered, and it is difficult to stably produce a yarn having a single fiber fineness of less than 1 dtex. On the other hand, when the single fiber fineness is larger than 2 dtex, the multifilament yarn constituting the fabric becomes difficult to take a finely packed structure, and it becomes difficult to obtain a low air permeability. The change increases the air permeability. Moreover, since the effect which reduces the rigidity of a multifilament yarn is acquired by making single fiber fineness into this range, the stowability of an airbag can also be improved.

  Regarding multifilament yarns constituting airbag fabrics, it has been studied for many years to reduce both the total fineness and the single fiber fineness, but less than 2 dtex within the range of the total fineness of 200 to 700 dtex as in the present invention. There is no example of actually producing a polyamide fiber having a single fiber fineness, and there is no example disclosed of the characteristics provided when a fabric for an airbag is constructed using such a polyamide fiber. This is because, in the conventional examination, the improvement in the characteristics of the base fabric tended to be saturated when the single fiber fineness was reduced to about 3 to 4 dtex, and the single fiber fineness of 100 or more single fibers and 2 dtex or less was obtained. This is because it was extremely difficult to stably produce industrial-use polyamide fibers by direct spinning and drawing methods. The present inventors diligently studied a method for obtaining a polyamide fiber having a single fiber number of 100 or more and 2 dtex or less by the method described later, and the characteristics of an airbag fabric composed of the polyamide fiber. As a result, when polyamide fibers differing only in single fiber fineness are used as a base fabric by the same method, the initial low air permeability, low air permeability after environmental degradation test, and compactness when stored by setting the single fiber fineness to 2 dtex or less It has been clarified that the sex and slip resistance are all improved. In particular, the low air permeability maintenance after the environmental degradation resistance test by setting the single fiber fineness to 1.8 dtex or less has been investigated to greatly exceed the value estimated from the conventional examination results. In addition, it is difficult to obtain a polyamide fiber suitable for an airbag having a single fiber fineness of less than 1 dtex even by using the method of the present invention.

The initial air permeability of the non-coated airbag fabric of the present invention needs to have a value of 0.50 L / cm ² / min or less when measured at a test differential pressure of 19.6 kPa, preferably 0.40 L / cm ^2. / Min or less. By adjusting the air flow rate to the above range, the inflation gas emitted from the inflator at the time of a collision can be used effectively without leakage, the airbag deployment performance is improved, and the occupant can be reliably received. When the air permeability exceeds 0.50 L / cm ² / min, the inflated state of the airbag cannot be maintained due to the collision of the occupant, and the occupant restraint property is inferior. The initial air permeability when measured at a test differential pressure of 19.6 kPa refers to a value measured by the method described in the measurement method “(14) Initial air permeability” in the column of Examples described later.

In addition, it is important that the air permeability after the environmental aging test of the non-coated airbag fabric of the present invention does not exceed 150% of the initial air permeability. Airbags are installed in automobiles for a long period of 10 to 20 years, and during that time, they are exposed to various environments such as high and low temperatures such as summer and winter, as well as high and low humidity. As a result of diligent examination of which environment affects the air permeability of the fabric, the present inventors have made the heat permeability most deteriorated, and the air permeability after the heat aging test is 150% of the initial air permeability. It has been found that not becoming larger can maintain low air permeability in all environments. The heat aging test is a test method in which a fabric is treated for 400 hours without being strained in a temperature atmosphere of 120 ° C. After the test, the fabric is left to stand at 20 ° C. and 65% RH for 24 hours. The air permeability is measured at a pressure of 19.6 kPa. Specifically, it means a value measured by the method described in the measurement method “(15) Air permeability after heat aging test” in the column of Examples described later. Usually, in order to set the bag deployment performance based on the initial air permeability, the air bag has a larger air permeability after the heat aging test than 150% in comparison with the initial air permeability. The gas leakage from the woven fabric constituting the vehicle increases, and the passenger cannot be reliably received. In addition, when the air permeability of the heat aging test degree is larger than 150% in comparison with the initial air permeability, conversely, the air bag deployment performance is set on the assumption that the air permeability increases after long-term equipment (for example, the vent hole is made smaller). In such a case, immediately after using the vehicle, that is, before long-term installation, gas leakage from the airbag becomes too small, and on the contrary, damage to the occupant increases. Therefore, there is a need for a fabric that does not change air permeability under any circumstances. The air permeability of the heat aging test degree is preferably 140% or less, more preferably 130% or less with respect to the initial air permeability. The air permeability after the heat aging test is preferably 0.50 L / cm ² / min or less in order to maintain the airbag in an inflated state for a while after receiving the occupant.

  As the tensile strength of the multifilament yarn constituting the airbag fabric of the present invention, both the warp yarn and the weft yarn are 8.0 to satisfy the mechanical properties required for the airbag fabric and from the viewpoint of the yarn production operation. 9.0 cN / dtex is preferable, and 8.3 to 8.7 cN / dtex is more preferable. At the same time, the elongation of the multifilament yarn is preferably 20 to 25%, in order to increase the toughness of the airbag fabric and the work of breaking, and from the viewpoint of improving the yarn-making property and weaving property. More preferably.

  The cover factor (CF) of the fabric is preferably 1800-2300. By adjusting the cover factor within this range, it is possible to achieve both a compact storability and low air permeability of the required fabric. By setting the cover factor to 1800 or more, the air permeability can be reduced. Moreover, compact storage property can be improved by making this cover factor 2300 or less.

Here, the cover factor (CF) of the woven fabric is a value calculated from the total fineness and woven density of the yarn used for the warp yarn or the weft yarn. The warp yarn total fineness is Dw (dtex), and the weft yarn total fineness. Is Df (dtex), the weft density of the warp yarn is Nw (lines / 2.54 cm), and the weave density of the weft yarn is Nf (lines / 2.54 cm).
CF1 = (Dw × 0.9) ^1/2 × Nw + (Df × 0.9) ^1/2 × Nf
Next, the manufacturing method of the polyamide multifilament yarn which is the preferable form which comprises the base fabric for airbags of this invention, and the method of manufacturing the base fabric for airbags are demonstrated.

  The polyamide multifilament yarn is preferably produced by the following method based on known melt spinning.

First, the above-mentioned polyamide chip is supplied to an extruder-type spinning machine, is distributed to a spinneret by a metering pump, and is melt-spun at an appropriate temperature (for example, 290 to 300 ° C. for nylon 66). At this time, the hole spec of the spinneret is an appropriate back pressure (for example, at least 60 kg / cm ² for nylon 66 in order to reduce the variation in single fiber fineness and suppress the occurrence of fluff during weaving, It is preferable to design to 80-120 kg / cm < ² >). Further, the discharge holes are arranged on concentric circles, and the number of rows is preferably 2 to 8 rows, more preferably 3 to 6 rows. If the number of rows is too small, the distance between single fibers will be too small, the single fibers will collide with each other during spinning, and if bad, they will be fused, and if too large, the physical properties between single fibers due to cooling spots will increase, which is preferable. Absent. Moreover, although the diameter when connecting each discharge hole arranged in the outermost periphery as a concentric circle is made smaller than the internal diameter of a heating cylinder or an annular cooling device, it is preferably 8 to 25 mm, more preferably 10 to 20 mm. If the position of the outermost hole is too close to the heating cylinder or the annular cooling device, the multifilament yarn before solidification tends to come into contact with the device and spinning becomes unstable, and if too far, cooling of the multifilament yarn is not possible. It becomes sufficient, and it becomes difficult to obtain a polyamide multifilament yarn having high strength and high elongation.

  The spun multifilament yarn discharged from the die is sequentially cooled and solidified by sequentially passing through a cylindrical heating tube and a cylindrical annular cooling device. If the single fiber fineness is 1.5 dtex or more, the heating cylinder may or may not be used, but when used, the inner diameter of the cylinder is made the same as that of the annular cooling device, so that the heating cylinder in the cylinder contacts the cooling device. It is preferable to prevent turbulence of the air flow at the location, and it is preferable to cool it using an annular cooling device after heating it so that the atmospheric temperature in the cylinder becomes 250 to 350 ° C. with a length of 50 to 100 mm. . If the heating cylinder length is too long, the thickness unevenness in the longitudinal direction of the polyamide multifilament yarn is greatly deteriorated, which is not preferable. On the other hand, when the single fiber fineness is less than 1.5 dtex, an annular cooling device is installed without using a heating cylinder, and cooling of the spun yarn is started more quickly so that the thickness unevenness in the longitudinal direction of the yarn is extreme. However, if the base surface temperature is lowered and the base surface temperature is lowered, it becomes difficult to obtain a polyamide multifilament yarn having high strength and high elongation. It is preferable to blow hot air of 100 to 250 ° C. at a constant length within 100 mm. In the cooling of the multifilament yarn by the annular cooling device, it is preferable to use a cooling air of 10 to 50 ° C. so that the polyamide can be sufficiently cooled to the glass transition point. A basic configuration of the annular cooling device may be used. For example, a cylindrical body is constituted by a porous member having a large number of capillary holes, and the cooling air sent into the cooling cylinder is blown out while being rectified in the longitudinal direction of the multifilament yarn from the cooling air blowing portion. What should I do? In order to adjust the cooling air speed, for example, it is preferable to install a porous member such as a punched plate or mesh in the air introduction portion of the cooling cylinder element. In order to obtain a high-strength and high-strength single-fiber fine-filament polyamide multifilament yarn, particularly nylon 66 multifilament yarn, which constitutes the airbag fabric of the present invention, it is preferable to have the following characteristics. .

  The cooling air is blown from the outer peripheral side of the discharge hole group to the center side. By adopting this configuration, it is possible to supply cooling air sufficient to sufficiently cool the polyamide multifilament yarn having a high degree of cooling difficulty as compared with the polyester type. When the structure is blown from the center side to the outer peripheral side, in order to obtain the polyamide multifilament yarn of the present invention, since the single fiber protrudes more than necessary, or an excessively long cooling facility is required, the size of the facility is large. This is not preferable because it leads to inconvenience.

  The length of the cooling cylinder is considerably longer than the conventionally proposed annular cooling equipment, and the blowout length of the cooling air is preferably in the range of 600 to 1200 mm, more preferably 800 to 1000 mm. If it is 600 mm or more, the polyamide multifilament yarn of the present invention can be sufficiently cooled, and good mechanical properties and fluff quality can be obtained. If it is 1200 mm or less, the equipment itself is not too long, which is preferable.

  The pressure difference between the inside of the cooling cylinder and the atmospheric pressure is preferably 500 to 1200 Pa, more preferably 600 to 1100 Pa, still more preferably 800 to 1000 Pa, and the cooling air is preferably blown. In the case of using a conventional horizontal blow cooling device, the fluff quality tends to deteriorate when the cooling air is weakened and the mechanical properties of the multifilament yarn are lowered. However, when an annular cooling device is used, the effect of the differential pressure on the physical properties of the polyamide multifilament of the present invention is small. For example, even if it is about 200 Pa, the mechanical properties can be adjusted only by adjusting the draw ratio. It was also found that the occurrence of fluff can be remarkably suppressed by setting the pressure to 500 Pa or more. Moreover, when it is set to 1200 Pa or less, the wind speed does not increase excessively and it is easy to prevent contact between yarns, which is preferable.

Further, the wind speed of the cooling air to said device longitudinally uneven, the upper side air speed _{V U} 10 to 30 m / min, to 40 to 80 m / min the lower side air speed _{V L, V U} is less than _{V L,} V it is preferable _L / _{V U} is 2-3. More preferable ranges of V _U and V _L are 15 to 25 m / min and 50 to 70 m / min, respectively. By changing the wind speed ratio in at least two stages in the longitudinal direction of the apparatus and setting the wind speed range, the fiber physical properties can be improved without deteriorating the thickness unevenness in the longitudinal direction of the multifilament yarn. In particular, by producing a slow cooling effect on the upper side, the toughness of the multifilament yarn is improved, and the elongation at the same strength changes by about 2 to 5%. With regard to such a change in the wind speed ratio, it is preferable to change the position at about 10 to 50% of the total length from the uppermost part of the cooling air blowing part, and more preferably 15 to 45%. As a means for this, by installing a donut-shaped porous member at a position where the ratio is to be changed between the outer cylinder of the cooling cylinder and the rectifying cylinder made of the porous member, the position is used as a boundary between the upper and lower parts of the cylinder. In addition, a means for changing the wind speed above and below by giving a differential pressure, and a means for adjusting the differential pressure between each cylinder and the atmospheric pressure with a two-stage cooling device itself can be considered. There is no problem.
When trying to produce a polyamide multifilament yarn having a total fineness of 200 to 700 dtex and a single fiber fineness of 1 to 2 dtex using a conventional horizontal blowing cooling facility, the yarn swinging at the spinning part becomes too intense, While the contact could not be suppressed, in the above-described method, the cooling air and the spun multifilament yarn are close to each other even if the cooling wind speed before solidification of the multifilament yarn is reduced. In addition, air collides with each other to form a descending air flow, and the horizontal velocity component of the cooling air can be greatly reduced. Therefore, it is presumed that the yarn can be produced while suppressing the yarn shaking.

  Thereafter, the obtained cooled multifilament yarn can be wound after being applied with an oil agent by a known method, taken up by a take-up roll, stretched, and then wound. As the oil agent, a known oil agent can be used. In order to suppress winding of the single yarn on the take-up roll, the adhesion amount is preferably 0.3 to 1.5% by weight, and more preferably 0.5 to 1%. 0.0% by weight.

  The spinning speed defined by the rotation speed of the take-up roll is preferably 500 to 1000 m / min, more preferably 700 to 900 m / min. When the spinning speed is 500 m / min or more, the final production speed is sufficient, and a polyamide multifilament yarn can be produced at a low cost. When the speed is 1000 m / min or less, yarn breakage and frequent occurrence of fluff can be prevented, which is preferable.

  The spun multifilament yarn obtained by these methods can be stretched, relaxed and heat-treated and wound using a known method, for example, multistage stretching at 100 to 250 ° C. in 2 to 3 stages. After heat treatment, it is possible to perform relaxation heat treatment at 50 to 200 ° C. at 1 to 10%.

  In addition, the entanglement to be applied to the multifilament yarn can be appropriately selected according to the type of loom and the weaving speed. However, if the method according to the present invention is used, it is not necessary to entangle excessively and entanglement of 15 to 30 pieces / m. What is necessary is just to change the kind and provision conditions of a confounding provision apparatus so that a number may be obtained. Even if it greatly falls below 15 pieces / m or exceeds 30 pieces / m, the high-order process passability tends to deteriorate. Similarly, the entanglement strength may be within a known range.

    Thus, a polyamide multifilament yarn suitable for an air bag having a total fineness of 200 to 700 dtex and a single fiber fineness of 1 to 2 dtex, which could not be produced by a conventionally proposed method, preferably has a strength of 8 to 9 cN / dtex and an elongation of 20 It is possible to obtain -25%, boiling water shrinkage of 4 to 10%, free from yarn unevenness, inexpensively and with excellent yarn-making properties and fluff quality. That is, by the direct spinning drawing method, the yarn can be efficiently produced using a multi-yarn simultaneous drawing method of 8 yarns or more at a spinning speed of 3000 m / min or more, more preferably 3500 m / min or more.

  In the airbag fabric of the present invention, first, the warp yarn having the above-mentioned material and fineness is warped and applied to a loom, and the weft yarn is similarly prepared. As such a loom, for example, a water jet room, an air jet room, a rapier room, and the like can be used. In particular, in order to increase productivity, it is preferable to use a water jet loom which is relatively easy to weave at high speed.

  Next, in the weaving, the warp yarn tension is preferably adjusted to 50 to 200 cN / line, more preferably 80 to 150 cN / line. By setting the tension within this range, the multifilament yarn bundle of warp yarns constituting the fabric is pressed against the multifilament yarn of the weft yarn, and the multifilament yarn bundle spreads to become an elliptical yarn bundle. It is effective to reduce the air permeability. When the warp yarn tension is less than 50 cN / string, it is difficult to reduce the gap between single fibers in the bundle of multifilament yarns constituting the woven fabric, and it is difficult to reduce the air permeability. On the other hand, if it is larger than 200 cN / fiber, fluffing occurs during weaving, which is not good in terms of productivity.

  As a specific method of adjusting the warp yarn tension within the above range, there is a method of adjusting the weft yarn feeding speed in addition to adjusting the warp yarn feeding speed of the loom. Whether the warp yarn tension is actually within the above range during weaving can be determined, for example, by measuring the tension applied to one warp yarn with a tension measuring instrument between the warp beam and the back roller while the loom is running. Can be confirmed.

  Further, it is preferable to make a difference of 10 to 90% between the tension of the upper thread and the tension of the lower thread in the warp thread opening. By doing so, the above-described warp yarn bending structure is promoted, the warp yarn and the weft yarn are pressed against each other strongly, the yarn bundle of the multifilament yarn spreads and becomes an elliptical yarn bundle, thereby reducing the air permeability. It is effective to make it.

  As a method of making a difference between the tension of the upper thread and the tension of the lower thread at the warp thread opening, for example, by setting the back roller at a higher position, the upper thread traveling line length and the lower thread traveling line length There is a way to make a difference. For example, by placing a guide roll between the back roller and the reed and shifting the opening fulcrum upward or downward from the warp line with this guide roll, the running line length of one yarn is longer than the other when opening. As a result, the tension increases and it becomes possible to make a difference between the tension of the upper thread and the tension of the lower thread. As the installation position of the guide roll, it is preferable to arrange the guide roll at a position of 20 to 50% from the back roller side with respect to the interval between the back roller and the wrinkle drawing. The position of the opening fulcrum is preferably 5 cm or more away from the warp line.

  In addition, as another method for making a difference between the tension of the upper thread and the tension of the lower thread, for example, a cam drive system is adopted for the opening device, and the dwell angle on one side of the upper thread / lower thread is 100 degrees or more than the other. There is also a way to take large. The tension increases when the dwell angle is increased.

  It is preferable to use a bar temple as the loom temple. This is because, when the bar temple is used, it is possible to beat the entire fabric before gripping, so that the gap between the synthetic fiber filaments can be reduced, and as a result, the low air permeability is improved.

  Next, when the weaving process is finished, processing such as scouring and heat setting is performed as necessary. About heat setting temperature, it is preferable to set it as 120 to 180 degreeC. When the temperature is less than 120 ° C., the fabric shrinks during the heat aging test, and the fabric structure changes. Therefore, a gap is generated at a portion where the warp yarn and the weft yarn cross, and the air permeability deteriorates after the heat aging test. On the other hand, when the temperature is higher than 180 ° C., the yarn in the woven fabric contracts at the time of heat setting, and a gap is generated at a portion where the warp yarn and the weft yarn intersect, thereby causing deterioration of the initial air permeability itself.

  The airbag fabric of the present invention is sewn into a bag shape and attached to an accessory such as an inflator to form an airbag, which can be used for a driver's seat, front passenger seat, rear seat, side airbag, etc. .

Hereinafter, the present invention will be described in detail by way of examples. The definition of each characteristic and the measuring method in the present invention are as follows.
[Measuring method]
(1) Total fineness: JIS L1013 (1999) 8.3.1 The positive fineness was measured at a predetermined load of 0.045 cN / dtex by the A method to obtain the total fineness.

  (2) Number of single fibers (number of filaments): Calculated by the method of JIS L1013 (1999) 8.4.

  (3) Single fiber fineness: It was calculated by dividing the total fineness by the number of single fibers obtained in (2) above.

  (4) Strength and elongation: Measured under constant speed elongation conditions shown in JIS L1013 8.5.1 standard time test. The sample was “TENSILON” UCT-100 manufactured by Orientec Co., Ltd., and the gripping interval was 25 cm and the pulling speed was 30 cm / min. In addition, elongation was calculated | required from elongation of the point which showed the maximum strength in a SS curve.

(5) Boiling water shrinkage ratio: Sampling the raw yarn in a crushed shape, adjusting the temperature in a temperature / humidity adjustment chamber at 20 ° C. and 65% RH for 24 hours or longer, and applying a load equivalent to 0.045 cN / dtex to the sample for a long time The thickness L ₀ was measured. Next, after immersing the sample in boiling water for 30 minutes in an unstrained state, the sample was air-dried for 4 hours in the temperature / humidity adjusting chamber, and a length L ₁ was measured by applying a load equivalent to 0.045 cN / dtex to the sample again. did. The boiling water shrinkage was calculated from the respective lengths L ₀ and L _{1 according} to the following equation.
Boiling water shrinkage = [(L ₀ −L ₁ ) / L ₀ ] × 100 (%)
(6) Fluff evaluation: The obtained fiber package was rewound at a speed of 500 m / min, and a laser type fluff detector “Flytec V” manufactured by Heberline was installed at a location 2 mm away from the multifilament yarn being rewound, and detected. The total number of fluffs converted was displayed in terms of the number per 100,000 m.

(7) Wind speed: An anemono master manufactured by KANOMAX was closely attached to the cooling air outlet at each measurement point. The measuring points are 0, 50, 100 mm from the upper end of the cylinder constituting the cooling air outlet, and every 100 mm up to the lower end of the cylinder every 100 mm, changing the angle by 90 degrees in the circumferential direction. The wind speed average of these four points was taken as the wind speed at each distance from the upper end of the cooling air blowing section. Next, when the vertical wind speed is changed due to equipment, the upper side and the lower side are drawn at the changed position, and when the intentional change of the wind speed ratio is not performed, the upper side and the lower side at a position 300 mm from the upper end. drawn to the side, it was determined respectively V _U and V _L by dividing the interval wind speed integrated by the effective cooling length.

For example, when the wind speed at the position a (mm) from the upper end of the cylinder is Va (m / min) and the cooling air blowing length is L (mm), the wind speed ratio is intentionally changed at a position of 350 mm. The calculation method of is as follows.
_{V U = [50 (V 0} + 2V 50 + V 100) +100 (V 100 + V 200) +150 (V 200 + V 300)] / 2/350
V _L = [150 (V ₄₀₀ + V ₅₀₀ ) +100 (V ₅₀₀ + V ₆₀₀ ) +...] / 2 / (L−350)
Note that... Means that the maximum measurement point is similarly calculated and added after 600 mm.

(8) Fabric thickness According to JIS L 1096: 1999 8.5, using a thickness measuring device at five different points of the sample, after waiting for 10 seconds under pressure of 23.5 kPa to settle the thickness The thickness was measured and the average value was calculated.

(9) Weft density of warp and weft yarns Measured based on JIS L 1096: 1999 8.6.1.
The sample was placed on a flat table, and the number of warp yarns and weft yarns in a 2.54 cm section was counted at five different locations, excluding unnatural wrinkles and tension, and the average value was calculated.

(10) Fabric weighting In accordance with JIS L 1096: 1999 8.4.2, three test pieces of 20 cm × 20 cm were collected, each mass (g) was measured, and the average value was the mass per 1 m ² (g / M ² ).

(11) Tensile strength of woven fabric JIS K 6404-3 In accordance with test method B (strip method), for each of the vertical and horizontal directions, five test pieces were collected, the yarn was removed from both sides of the width to a width of 30 mm, and a constant speed tension type testing machine, The test piece was pulled at a grip interval of 150 mm and a tensile speed of 200 mm / min, and the maximum load until cutting was measured, and the average value was calculated for each of the vertical and horizontal directions.

(12) Elongation at break of fabric JIS K 6404-3 In accordance with test method B (strip method), for each of the vertical direction and the horizontal direction, five test pieces are sampled, the thread is removed from both sides of the width to make a width of 30 mm, and 100 mm intervals are provided at the center of these test pieces. With a marked line, with a constant-speed tension type testing machine, pull until the specimen is cut at a grip interval of 150 mm and a pulling speed of 200 mm / min, read the distance between the marked lines when reaching the cutting, The breaking elongation was calculated, and the average value was calculated for each of the vertical and horizontal directions.
E = [(L-100) / 100] × 100
Where E: elongation at break (%),
L: Distance (mm) between marked lines at the time of cutting.

(13) Tear strength JIS K 6404-4 According to test method B (single tongue method), test specimens with a long side of 200 mm and a short side of 76 mm were taken on the vertical and horizontal sides, respectively, and 5 specimens were collected respectively, and the test piece was perpendicular to the center of the short side. A 75 mm incision was made, and the specimen was torn with a constant speed tension type tester at a grip interval of 75 mm and a tensile speed of 200 mm / min until the specimen was pulled, and the tear load at that time was measured. From the obtained chart recording line of the tearing load, three points were selected from the maximum points excluding the first peak in descending order, and the average value was taken. Finally, an average value was calculated for each of the vertical and horizontal directions.

(14) Initial air permeability According to JIS L 1096: 1999 8.27.1 A method (Fragile type method), the air permeability when tested at a test differential pressure of 19.6 kPa was measured. Samples of about 20cm x 20cm are collected from 5 different locations of the sample, attached to one end of a cylinder with a diameter of 100mm, fixed so that there is no air leakage from the mounting location, and a test differential pressure using a regulator. It adjusted to 19.6 kPa, the air quantity which passes a test piece at that time was measured with the flowmeter, and the average value about five test pieces was computed.

(15) Air permeability after heat aging test Samples of about 20cm x 20cm are collected from 5 different locations and the tension is not applied to the test pieces in a dryer adjusted to 120 ± 2 ° C. Then, heat treatment was performed for 400 hours. Thereafter, the test piece was taken out from the dryer, and allowed to stand for 24 hours in an atmosphere of 20 ± 2 ° C. and 65 ± 5% RH. Then, the air permeability was measured by the same method as the initial air permeability, and the average of the five test pieces was measured. The value was calculated.

(16) Warp Thread Tension Using Check Master (registered trademark) (type: CM-200FR) manufactured by Kanai Koki Co., Ltd., the warp beam and the back roller are added per warp yarn at the center of the warp beam and back roller during operation. Tension was measured.

(17) Upper thread tension and lower thread tension at the warp yarn opening Stop the loom with the warp yarn open, and place a guide roll between the back roller and the squeezer (the back roller and the heel). If there is a tension between the guide roll and the wrinkle), the tension applied to the upper one warp thread is the same as the tension measuring machine used in (9) above. As measured. Similarly, the tension applied to one warp yarn on the lower side was measured as the tension of the lower yarn.

[Example 1]
(Vertical / Horizontal)
A nylon 66 chip obtained by liquid phase polymerization was mixed with a 5 wt% aqueous solution of copper acetate as an antioxidant and adsorbed by 68 ppm as copper with respect to the polymer weight. Next, a 50 wt% aqueous solution of potassium iodide and a 20 wt% aqueous solution of potassium bromide were added and adsorbed to 100 parts by weight of the polymer chip to 0.1 parts by weight as potassium, respectively, and a batch type solid state polymerization apparatus was used. Thus, solid phase polymerization was performed to obtain nylon 66 pellets having a relative viscosity of sulfuric acid of 3.8. The obtained nylon 66 pellets were supplied to an extruder, and the amount of discharge was adjusted by a metering pump so that two multifilament yarns having a total fineness of Table 1 were obtained, which were arranged in a spinneret and melt-spun at 295 ° C. Here, the relative viscosity of sulfuric acid is a value obtained by dissolving 2.5 g of a sample in 25 cc of 96% concentrated sulfuric acid and using an Ostwald viscometer at a constant temperature in a thermostatic bath at 25 ° C. Each spinneret is capable of obtaining two multifilament yarns having the number of single fibers shown in Table 1, that is, four concentric circles having a diameter of 0.22 mm, which is twice the number of single fibers shown in Table 1. The diameter when the outermost discharge hole group was concentrically connected was 14 mm smaller than the inner diameter of the heating cylinder and the cooling cylinder. A 100 mm heating cylinder heated to 300 ° C. is provided immediately below the base, and using the cylindrical annular cooling device having the cooling air blowing length shown in Table 1, the cooling air at 20 ° C. is cooled between the inside of the cooling cylinder and the atmospheric pressure. The spun multifilament yarn was cooled and solidified by pressurizing and blowing so that the differential pressure was the value shown in Table 1. “Fujibon” manufactured by Fuji Filter, which was formed into a cylinder by spirally winding a phenolic resin-impregnated cellulose ribbon having a thickness of 4.6 mm and a filtration accuracy of 40 μm as the cylinder constituting the cooling air blowing part of the cooling cylinder. Using. Further, a punching plate having a donut shape and an aperture ratio of 22.7% was arranged at a position 350 mm from the upper end of the cooling air blowing portion of the cooling cylinder so as to change the speed of the cooling air in the upper and lower sides of the cylinder. Next, a non-aqueous oil agent having a smoothing agent or the like was applied to the cooled and solidified multifilament yarn, wound around a spinning take-up roller, and the spun multifilament yarn was taken up. Subsequently, the multifilament yarn was continuously supplied to the drawing / heat treatment zone, and a nylon 66 multifilament yarn was produced by a direct spinning drawing method. At this time, the rotation speed of the drawing roller having the highest rotation speed (hereinafter referred to as drawing speed) is set to a constant speed of 3600 m / min, and the overall drawing ratio expressed by the take-off speed and the drawing speed ratio is the value shown in Table 1. Thus, the rotation speed of the take-up roller was adjusted.

The taken-up multifilament yarn is stretched by 5% between the take-up roller and the yarn feeding roller, and then 1 so that the rotational speed ratio between the rollers becomes 2 between the yarn feeding roller and the first drawing roller. Second-stage stretching was performed between the first stretching roller and the second stretching roller. Subsequently, a relaxation heat treatment of 6% was performed between the second drawing roller and the relaxation roller, the multifilament yarn was entangled with the entanglement imparting device, and then wound with a winder. The surface temperature of each roller was set so that the take-up roller was normal temperature, the yarn feeding roller was 40 ° C., the first stretching roller was 140 ° C., the second stretching roller was 230 ° C., and the relaxation roller was 150 ° C. Further, the application amount of the non-aqueous oil agent was adjusted so that the amount of oil adhering to the yarn became 1.0% by weight. The entanglement process was performed by injecting high-pressure air from the direction perpendicular to the traveling multifilament yarn in the entanglement imparting device. A guide for regulating the traveling multifilament yarn was provided before and after the entanglement imparting device, and the pressure of the jetted air was constant at 0.35 MPa.
Table 1 shows the fiber production conditions including the upper and lower average wind speed measurements in the cooling cylinder and the properties of the resulting nylon 66 multifilament yarn.

  Table 1 also shows the results obtained by winding 50 kg of nylon 66 multifilament yarn produced using the above method at a speed of 500 m / min and examining the fluff present in the fiber package using a laser type fluff detector. .

  The obtained nylon 66 multifilament yarn had sufficient mechanical properties, and a polyamide multifilament yarn with less fluff could be obtained.

  Composed of the obtained nylon 66, having a circular cross-sectional shape, a single fiber fineness of 1.8 dtex, a filament number of 192, a total fineness of 350 dtex, no twist, a strength of 8.5 cN / dtex, and an elongation of 23.5% Fiber multifilament yarn was used as warp and weft.

(Weaving process)
Using the warp yarn and the weft yarn, a woven fabric having a warp yarn weaving density of 56 yarns / 2.54 cm and a weft yarn weaving density of 63 yarns / 2.54 cm was woven.

  A water jet loom is used as a loom, a bar temple is installed between the hammering portion and the friction roller to grip the fabric, and the warp is positioned at a position 40 cm from the back roller to the back roller. A guide roll was attached so as to lift the 7 cm warp yarn from the line.

  The weaving conditions were adjusted so that the warp yarn tension during weaving was 147 cN / main, the upper yarn tension when the loom was stopped was 118 cN / main, the lower yarn tension was 167 cN / main, and the loom rotation speed was 500 rpm. did.

(Heat setting process)
Subsequently, this fabric was subjected to a heat setting process at 160 ° C. for 1 minute using a pin tenter dryer under the dimensional regulation with a width insertion rate of 0% and an overfeed rate of 0%.

  The characteristics of the obtained airbag fabric are shown in Table 2. The obtained air bag fabric was excellent in the initial low air permeability and had little change in air permeability after the heat aging test.

[Comparative Example 1]
(Vertical / Horizontal)
By uniformly blowing a cooling air of 30 m / min from a horizontal blow cooling device having a length of 1500 mm, a multifilament yarn having a total fineness of 350 dtex and a single filament number of 136 is drawn at a drawing speed of 3200 m / min. To be able to get. A spinneret was prepared in the same manner as in Example 1 except that nylon 66 multifilament yarn was manufactured under the conditions shown in Table 1 using an array in which the minimum value of the discharge hole interval was 7.5 mm. .

  Composed of the obtained nylon 66, having a circular cross-sectional shape, a single fiber fineness of 2.6 dtex, a filament number of 136, a total fineness of 350 dtex, no twist, a strength of 8.5 cN / dtex, and an elongation of 23.5% Fiber multifilament yarn was used as warp and weft.

(Weaving process and heat setting process)
The same weaving and heat setting processing as in Example 1 was performed.

  The characteristics of the obtained airbag fabric are shown in Table 2. The obtained airbag fabric had a high initial air permeability and a large change in air permeability after the heat aging test.

[Comparative Example 2]
(Vertical / Horizontal)
The same yarns as those used in Example 1 were used as warp yarns and weft yarns.

(Weaving process)
Using the above warp yarn and weft yarn, under the same weaving conditions as in Example 1, a woven fabric having a warp yarn weaving density of 56 yarns / 2.54 cm and a weft yarn weaving density of 63 yarns / 2.54 cm was woven.

(Heat setting process)
Subsequently, this fabric was subjected to a heat setting process at 100 ° C. for 1 minute using a pin tenter dryer under the dimensional regulation of a width insertion rate of 0% and an overfeed rate of 0%.

  The characteristics of the obtained airbag fabric are shown in Table 2. The obtained air bag fabric had no problem in the initial air permeability, but had a large change in air permeability after the heat aging test.

  The airbag fabric according to the present invention has excellent low breathability required for airbag fabric, and maintains excellent low breathability even after being installed in an automobile for a long period of time. Therefore, the airbag fabric of the present invention can be suitably used particularly for a driver seat, a passenger seat, a side airbag for side collision, and the like, but the application range is not limited thereto.

Claims (2)

The airbag fabric is made of synthetic fiber multifilament yarn having a total fineness of 200 to 700 dtex and a single fiber fineness of 1 to 2 dtex, and the initial air permeability of the fabric is 0.00 when measured at a test differential pressure of 19.6 kPa. 50 L / cm ² / min or less, and the air permeability after the fabric is subjected to heat aging treatment in an environment of 120 ° C. for 400 hours is 150% or less with respect to the initial air permeability. Non-coated airbag fabric. The non-coated airbag fabric according to claim 1, wherein the air permeability after the heat aging treatment is 0.50 L / cm ² / min or less.