JP4306391B2 - Airbag base fabric and manufacturing method thereof - Google Patents

Description

  The present invention relates to an airbag base fabric constituting an airbag used as an automobile safety device, and more particularly to a method of manufacturing a low-breathability base fabric without impairing mechanical properties.

  In recent years, many automobiles are equipped with airbags as one of safety devices. When a sensor detects that an automobile body has been impacted in the event of a collision, the airbag is operated by supplying high-temperature and high-pressure gas from the inflator into the airbag and rapidly deploying the airbag in the vehicle. It is a device that alleviates the impact received by passengers and passengers, for example, a device that prevents the head from crashing into a handle, a windshield, a door glass, etc., and further prevents the body from jumping out in the collision direction.

  An airbag base fabric constituting such an airbag is generally manufactured by weaving multifilament yarns made of synthetic fibers and shrinking the resulting fabric. In order to improve the property, air barrier property (low air permeability), flame retardancy, etc., a coating base fabric in which the surface of the fabric is coated with a synthetic rubber such as chloroprene, chlorosulfonated olefin, or silicone has been used. However, the base fabric coated on the surface is heavy, and the flexibility is lowered, the storage property is deteriorated, and the production cost is high, so that there are many problems in using as a base fabric for an air bag. In order to solve these problems, a base fabric coated with silicone instead of synthetic rubber coating was developed. However, even this base fabric could not completely solve the above problems.

  Therefore, recently, non-coated airbags using a non-coated base fabric (non-coated airbag base fabric) have become the mainstream, improving weight reduction and storage. Various techniques have been proposed to further improve the air barrier property (low air permeability) of the non-coated airbag base fabric.

  For example, Patent Document 1 proposes performing calendaring on both sides of a fabric as a method of manufacturing a fabric for an air bag having low air permeability. However, calendering can achieve a certain degree of low air permeability, but the cost is inevitable because the manufacturing process is increased. Moreover, when calendering is performed, the flexibility of the base fabric is impaired and the storage property is deteriorated.

  Patent Document 2 proposes that a chemical shrinkage treatment is applied to a fabric when manufacturing a vehicle airbag base fabric. However, if the number of steps is increased for chemical shrinkage treatment, the cost increases, and the fabric strength may decrease due to chemical treatment. Therefore, a problem occurs in reliability as an airbag.

Patent Document 3 proposes a non-coated airbag fabric using a yarn in which thermoplastic synthetic fiber yarns having different single yarn finenesses are mixed. However, a separate process for producing thermoplastic fiber yarns having different single yarn fineness is required, which is complicated.
Japanese Patent Laid-Open No. 4-2835 JP-A-6-41844 (see [Claims] and [0005]) JP-A-8-325888 (see [Claims] and [0017])

  This invention is made | formed in view of such a condition, The objective is obtained by the method of manufacturing a low air permeability base fabric simply, without increasing a manufacturing process, and this manufacturing method. It is providing the base fabric for airbags.

  The method for producing an airbag base fabric according to the present invention, which has solved the above-mentioned problems, refers to a method for weaving a multifilament yarn made of synthetic fibers and subjecting the resulting fabric to shrinkage to produce an airbag fabric base. A method of manufacturing, wherein the multifilament yarn is composed of a single yarn having a flatness of 1.2 to 6 and has a boiling water shrinkage of 5 to 15%. The gist is that the warp tension is suppressed to 0.08 cN / dtex or less.

  As the single yarn, it is preferable to use a polyamide fiber, and it is preferable to use hot water for the shrinking process. The woven fabric obtained by weaving is preferably subjected to shrinkage processing without drying.

According to the said manufacturing method, the base fabric for airbags whose air permeability under 20 kPa differential pressure is 0.50 L / cm < ² > / min or less are obtained.

  According to the present invention, since it is not necessary to increase the number of steps when manufacturing the airbag fabric, the low-breathable airbag substrate is maintained while maintaining the mechanical characteristics required for the airbag fabric. Cloth can be provided at low cost. The airbag fabric obtained by the production method of the present invention is particularly useful as a non-coated airbag fabric.

  As described above, if the number of steps is increased in order to increase the low air permeability of the airbag fabric, the cost increases. Therefore, the present inventors have conducted intensive studies on measures for increasing the low air permeability of the airbag fabric without increasing the number of steps. As a result, while using a flat single yarn as the material of the base fabric, specify the hot water shrinkage rate of the multifilament yarn made of the single yarn, and further loosen the warp tension when shrinking the fabric, the above The present invention has been completed by finding that the problem can be solved brilliantly. Hereinafter, the function and effect of the present invention will be described.

  The airbag fabric of the present invention is manufactured by weaving multifilament yarns made of synthetic fibers and shrinking the resulting fabric. Here, the multifilament yarn is a yarn obtained by collecting a plurality of single yarns (monofilaments) made of synthetic fibers.

  The type of synthetic fiber that can be used in the present invention is not particularly limited. For example, aliphatic polyamide fibers such as nylon 66, nylon 6, nylon 46, and nylon 12, aromatic polyamide fibers such as aramid fiber, polyethylene terephthalate, and poly Polyester fibers such as butylene terephthalate are used. Also, wholly aromatic polyester fibers, ultrahigh molecular weight polyethylene fibers, PPS fibers, polyether ketone fibers, and the like can be used. However, it is preferable to use polyamide fiber or polyester fiber in consideration of economy, and polyamide fiber is particularly preferable in consideration of characteristics as a raw material.

  The raw material of the synthetic fiber may be partly or wholly reused, and may contain various additives in order to improve process passability in the raw yarn manufacturing process and post-processing process. Good. Examples of the additive include an antioxidant, a heat stabilizer, a smoothing agent, an antistatic agent, a thickener, and a flame retardant. Of course, the synthetic fiber may be colored yarn.

  The multifilament yarn used in the present invention is a collection of a plurality of single yarns made of the above synthetic fibers. In the present invention, it is important to use a single yarn having a cross-sectional shape of 1.2 to 6 in cross section. . That is, a normal single yarn cross section is a circular shape having a flatness of about 1.0 (hereinafter sometimes referred to as “circular single yarn”), but in the present invention, a single yarn having a flat cross section (hereinafter referred to as “flat single yarn”). May be referred to as “thread”).

  In the present invention, a plurality of flat single yarns are collected to form a multifilament yarn, and the multifilament yarn is woven into a woven fabric. At this time, by arranging the single yarns to be stacked in the minor axis direction of the cross section, the gap per unit area in the cross section of the woven fabric is reduced. Therefore, compared to a fabric woven using a multifilament yarn obtained by collecting a plurality of circular single yarns having the same degree of fineness, a fabric obtained using flat single yarns even if the weave density is similar. This can reduce the amount of ventilation when the airbag is deployed. In addition, when a fabric having the same air flow rate as that of a fabric obtained using a circular single yarn is designed using a flat single yarn, the total fineness of the fabric can be reduced, and the fabric is thinned. A lightweight and flexible base fabric.

  In order to obtain such an effect, it is necessary to use a flat single yarn having a flatness of 1.2 to 6. This is because when the flatness is less than 1.2, the above-mentioned effect due to flatness is not effectively exhibited. More preferably, the multifilament yarn is composed of flat single yarns having a flatness of 1.5 or more, and more preferably a flatness of 2.0 or more. On the other hand, when the flatness exceeds 6, it becomes easy to break when producing a flat single yarn, and also causes fluff. It is recommended that the multifilament yarn is composed of flat single yarns having a flatness of 5.0 or less, more preferably 4.0 or less.

  When a multifilament yarn is composed of flat single yarns, it is not necessary that all flat single yarns have the same flatness, and flat single yarns having different flatnesses may be mixed at an arbitrary ratio. In this case, in order to effectively exhibit the effect of flatness, the ratio of flat single yarns having the same flatness to the total number of flat single yarns constituting the multifilament yarn is preferably 50% or more, and more preferably Is over 70%.

  In the present invention, the flatness of the single yarn cross section is defined as the ratio of the major axis to the minor axis (major axis / minor axis), which approximates the shape of the single yarn section to an ellipse. In FIG. 1, an example of the cross-sectional shape of the flat single yarn in this invention is shown. In the figure, a represents the long diameter of the flat single yarn, b represents the short diameter of the flat single yarn, and the flatness is calculated by calculating a / b. In addition, the cross-sectional shape shown in FIG. 1 is a typical example, Comprising: The cross-sectional shape of the flat single yarn of this invention is not restrict | limited to this. That is, the cross-section of the flat single yarn does not need to be a complete ellipse, and may have protrusions or depressions in part as long as the flatness as a whole is not affected. Further, as shown in FIG. 1, it is not necessary to be symmetrical. Even in such a case, the flatness may be calculated by approximating an ellipse so as not to impair the overall outer shape, with the longest diameter as the long diameter a and the shortest diameter as the short diameter b. A preferred cross-sectional shape is an ellipse.

  Specifically, the flatness of the single yarn cross section is obtained by taking a cross-sectional photograph of a fabric prepared according to JIS standard L 1096 (6) with a scanning electron microscope (SEM), By obtaining the longest part as a1 and the shortest part as b1 on the basis of the unit length, and dividing these by the observation magnification T (times) as the major axis a and the minor axis b, respectively, and calculating a / b calculate.

  In the present invention, it is preferable to use a flat single yarn having a fineness of 1 to 6 dtex. If the fineness of the flat single yarn is less than 1 dtex, the single yarn itself is thin and difficult to spin, and the flat effect is difficult to obtain. On the other hand, when the fineness of the flat single yarn exceeds 6 dtex, the flexibility of the finally obtained woven fabric is impaired, the storage property is deteriorated, and there is a tendency to be disadvantageous from the viewpoint of influence on the human body. More preferably, it is desirable to use a flat single yarn having a fineness of 5 dtex or less. The fineness of the flat single yarn is calculated by dividing the total fineness of the multifilament yarn described later by the number of flat single yarns constituting the multifilament yarn.

  In the present invention, it is important to use a multifilament yarn having a boiling water shrinkage of 5 to 15%. When the boiling water shrinkage rate is less than 5%, even when flat single yarn is used, the filling rate (denseness) during shrinkage processing is not sufficiently increased, and low air permeability cannot be obtained. More preferably, it is desirable to use a multifilament yarn having a boiling water shrinkage of 7% or more. On the other hand, if the boiling water shrinkage rate exceeds 15%, the fabric (base fabric) after shrinkage processing becomes too thick and impairs storage. More preferably, it is recommended to use a multifilament yarn having a boiling water shrinkage of 12% or less. The boiling water shrinkage is a value measured at 100 ° C. according to JIS standard L 1013 (8.18.1 hot water shrinkage B method).

  In the present invention, it is preferable to use a multifilament yarn having a total fineness of 100 to 700 dtex. This is because if the total fineness is less than 100 dtex, the tensile strength and tear strength tend to be insufficient, and it is more preferable to use a multifilament yarn having a total fineness of 120 dtex or more. On the other hand, when the total fineness exceeds 700 dtex, the strength is not affected, but the flexibility of the finally obtained fabric is impaired and the storage property is deteriorated. In addition, the surface of the fabric becomes hard, and there is a risk of damaging the human body in the event of a collision. A more preferable total fineness of the multifilament yarn is 500 dtex or less. The total fineness of the multifilament yarn can be measured according to JIS standard L 1013 (A method of 8.3.1).

  Next, the manufacturing method according to the present invention will be described.

  The synthetic fiber that can be used in the present invention is obtained by spinning a synthetic resin from a die by a usual melt spinning method. The spinning conditions vary depending on the type of synthetic resin (polymer) used as a raw material for the synthetic fiber, and appropriate conditions may be selected in consideration of the viscosity and thermal characteristics of the polymer. In general, in order to prevent deterioration of the polymer due to heat, it is preferable to shorten the residence time of the polymer in the spinning machine, and it is usually preferable to set it within 10 minutes. More preferably, it is recommended to be about 1 to 5 minutes.

  For example, when a synthetic resin is obtained as a synthetic resin using polyethylene terephthalate or polyhexamethylene adipamide as a raw material, the spinning temperature is set to 280 to 310 ° C., and the length is about 5 to 50 cm immediately below the die. It is preferable to provide a heating cylinder in which the relative humidity is controlled to about 200 to 350 ° C. and relative humidity to about 85%, and to pass through the heating cylinder. By passing through the heating cylinder, solidification of the molten polymer can be delayed and high strength can be expressed. The length, temperature, and relative humidity conditions of the heating cylinder depend on the fineness and flatness of the synthetic fiber (single yarn) to be obtained, and the number of single yarns when the single yarns are combined to obtain a multifilament yarn. Optimized. It is also effective to seal the atmosphere in the heating cylinder with a high-temperature inert gas as necessary in order to suppress thermal deterioration caused by raising the temperature in the heating cylinder.

  Here, in order to control the flatness of the cross-section of the synthetic fiber (single yarn) within the above range, for example, a direct spinning method in which a deformed hole is used as the die and a polymer is discharged from the deformed die hole, or composite spinning is used. A method of removing at least one component after simultaneously discharging two or more kinds of polymers using a method may be applied. When the composite spinning method is applied, a flat single yarn (monofilament) having a small single yarn fineness can be obtained by removing at least one component after drawing or fabric production. In view of ease of yarn production and ease of process, it is preferable to use a die having a deformed hole.

  In order to control the fineness of the flat single yarn and the total fineness of the multifilament yarn within the above ranges, it can be adjusted by changing the size of the die or determining the discharge amount of the polymer and the number of holes according to a known method. In order to collect the flat single yarn to obtain a multifilament yarn, for example, a method using a porous die or a method of combining polymers discharged from a plurality of die can be employed. In order to control the boiling water shrinkage of the multifilament yarn within the above range, for example, it can be adjusted by controlling the roller temperature and the relaxation rate during drawing.

  Next, the spun yarn passes through the high-temperature atmosphere as described above, and is then cooled and solidified with cold air. After the oil agent is applied, the spun yarn is taken up by a take-up roll that controls the spinning speed. The unstretched yarn taken up by the take-up roll is usually drawn continuously, but can be drawn in a separate step after being wound up. The spinning speed is usually 2000 m / min or less, and a conventional thermal stretching is adopted for the stretching. Stretching is preferably multistage stretching of two or more stages, and the draw ratio varies depending on the birefringence of the unstretched yarn, the stretching temperature and the stretch ratio distribution during multistage stretching, etc., preferably 1.5 to 6.0 times, More preferably, it is 2.0 to 5.5 times.

  Next, the stretched yarn is heat-set according to a conventional method. At this time, the tension and temperature during heat setting may be changed.

  In the drawing process and the heat setting process, the running yarn may be entangled. For the entanglement, a known method such as air entanglement can be adopted. In the case of air entanglement, an appropriate degree of entanglement can be achieved by appropriately changing the air pressure according to, for example, the fineness and tension of the yarn used.

  Next, a woven fabric is obtained by weaving the multifilament yarn.

  In order to produce a base fabric for an airbag using the multifilament yarn made of the synthetic fiber, the obtained multifilament yarn is used as it is for warp and weft and is woven by a normal method. At this time, it is not necessary to twist or glue.

  The weaving method is not particularly limited, but plain weaving is good considering the uniformity of the physical properties of the base fabric. The warp and weft yarns used may not be single. For example, the thickness of the multifilament yarn, the number of single yarns constituting the multifilament yarn, and the type of fiber may be different. The loom is not particularly limited, for example, an air jet loom, a rapier room, a water jet loom, etc., but it is preferable to use a water jet loom in terms of productivity and quality.

  In the production method of the present invention, the warp tension when weaving the fabric is preferably set to 0.1 to 0.30 cN / dtex. If the warp tension exceeds 0.30 cN / dtex, the cross section of the single yarn is easily aligned and the fabric becomes less breathable, but there are significant disadvantages in terms of production such as causing warp breakage. On the other hand, if the warp tension is less than 0.1 cN / dtex, the fabric becomes thick.

  Next, the obtained woven fabric is subjected to shrinkage processing and then dried. This is because by applying shrinkage to the woven fabric, the weave is clogged and the low air permeability of the airbag fabric is improved.

  In the present invention, it is important to suppress the warp tension to 0.08 cN / dtex or less in this shrinking process. That is, in the present invention, a multifilament yarn made of a flat single yarn having a specific single surface shape and having a specific hot water shrinkage rate is used, and the warp tension in the shrinking process is kept as small as possible. The formed multifilament yarn having a predetermined heat shrinkage rate is sufficiently shrunk to form an air bag base fabric having a texture. That is, when the warp tension exceeds 0.08 cN / dtex, the stress when the fabric is contracted becomes too large, and the gap between the fibers becomes large, and as a result, a low-breathable base fabric cannot be obtained. It is recommended to keep the warp tension to 0.06 cN / dtex or less. Note that if the warp tension is too small, the effect of the shrinking process becomes insufficient and it is difficult to achieve low air permeability of the airbag fabric, so it is recommended that the warp tension be at least 0.03 cN / dtex or more. The

  In the present invention, it is preferable to keep the residual dry heat shrinkage of the woven fabric (airbag base fabric) after shrinkage processing to 3% or less. The residual dry heat shrinkage refers to the shrinkage before and after drying of a woven fabric that has undergone shrinkage processing at 120 ° C. for 30 minutes. If the residual dry heat shrinkage exceeds 3%, the dimensional accuracy deteriorates.

  Examples of the shrink processing include hot water processing and heat setting processing typified by a pin tenter. The warp tension is set to 0.08 cN / dtex or less, and the residual dry heat shrinkage of the fabric after the shrink processing (120 ° C. × 30 In order to suppress the minute) to 3% or less, hot water processing using hot water for shrinkage processing is preferable. By using hot water in the shrinking process, hydrogen bonds in the fiber are cut, so that the warp tension can be reduced and the filling rate of the single yarn constituting the fiber can be increased without increasing the gap between the fibers. . When using hot water, a method of immersing the fabric obtained by the weaving in hot water or a method of spraying hot water on the fabric can be employed. The temperature of the hot water is preferably about 80-100 ° C. In addition, the woven fabric obtained by weaving may be subjected to shrinkage processing after drying once, but considering the production cost, the woven fabric obtained by weaving is subjected to shrinkage processing without drying, It is then preferred to perform a dry finish.

  The drying process is desirably performed at 150 ° C. or lower in order not to increase the air permeability of the airbag fabric. It should be noted that calendering, resin processing, coating processing, and the like may be performed after drying as long as the fabric after drying is in a range that can meet the purpose described above. However, it should be noted that adding such processing steps increases the manufacturing cost.

The airbag fabric obtained by the manufacturing method according to the present invention described above becomes a very low-breathable fabric having an air permeability of 0.50 L / cm ² / min or less under a differential pressure of 20 kPa. This contributes to the improvement of the initial restraint performance. The air permeability of the airbag fabric can be measured using, for example, a high-pressure air permeability tester (manufactured by OEM System Co., Ltd.).

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are not intended to limit the present invention, and may be implemented with appropriate modifications within a range that can meet the purpose described above and below. These are all possible and are within the scope of the present invention.

In the following examples or comparative examples, the flatness and fineness of the flat single yarn and the boiling water shrinkage and the total fineness of the multifilament yarn were measured by the following methods.
Flatness: A cross-sectional photograph of a fabric prepared in accordance with JIS standard L 1096 (6) was photographed with a scanning electron microscope (SEM), and the longest portion was measured based on the unit length on the photograph of a single yarn cross-section. a1, the shortest part was determined as b1, and the value divided by the observation magnification T (times) was defined as a major axis a and a minor axis b, respectively, and a / b was defined as flatness.
Fineness: Calculated by dividing the total fineness of the multifilament yarn by the number of flat single yarns constituting the multifilament yarn.
Boiling water shrinkage: Measured at 100 ° C. in accordance with JIS standard L 1013 (8.18.1 hot water shrinkage B method).
Total fineness: Measured according to JIS standard L 1013 (A method of 8.3.1).

Further, the air permeability and density of the obtained airbag fabric were measured by the following methods.
Air permeability: Measured under a differential pressure of 20 kPa using a high-pressure air permeability tester manufactured by OEM System Co., Ltd.
Density: Measured according to JIS standard L 1096 (8.8.1).

  In addition, the following warp density is the density of the warp which comprises the base fabric for airbags, and the following weft density is the density of the weft which comprises the base fabric for airbags.

Example 1
Nylon 66 fiber (flat single yarn) with a flatness of 3.3 in the single yarn cross section was used as a raw material for the synthetic fiber, and 96 flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 4.9 dtex, the boiling water shrinkage of the multifilament yarn is 8.0%, and the total fineness is 470 dtex.

  The obtained multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.25 cN / dtex in a water jet loom to obtain a woven fabric.

  The obtained woven fabric was immersed in hot water at 95 ° C. for shrinkage treatment, and then dried at 130 ° C. to obtain an airbag base fabric. The warp tension in the shrinking process was 0.06 cN / dtex.

  When the density of the obtained airbag fabric was measured, the warp density was 50 / 2.54 cm, and the weft density was 49 / 2.54 cm. Note that 2.54 cm is 1 inch.

  Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is apparent from Table 1, the obtained airbag fabric was a low-breathable fabric that satisfied the initial restraining performance when the airbag was deployed, and was a very excellent airbag fabric. .

Reference example 1
Nylon 66 fiber (flat single yarn) having a flatness of 2.8 in cross section of single yarn was used as a raw material for synthetic fibers, and 72 flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 4.9 dtex, the boiling water shrinkage of the multifilament yarn is 6.2%, and the total fineness is 350 dtex.

  The obtained multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.25 cN / dtex in a water jet loom to obtain a woven fabric.

  The obtained woven fabric was immersed in hot water at 98 ° C. for shrinkage treatment, and then dried at 130 ° C. to obtain a base fabric for airbag. The warp tension in the shrinking process was 0.07 cN / dtex.

  When the density of the obtained airbag fabric was measured, the warp density was 57 / 2.54 cm, and the weft density was 57 / 2.54 cm. Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is apparent from Table 1, the obtained airbag fabric was a low-breathable fabric that satisfied the initial restraining performance when the airbag was deployed, and was a very excellent airbag fabric. .

Example 2
Nylon 66 fiber (flat single yarn) having a flatness of 4.2 in the single yarn cross-section was used as a raw material for the synthetic fiber, and 96 flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 4.9 dtex, the boiling water shrinkage of the multifilament yarn is 8.2%, and the total fineness is 470 dtex.

  The obtained multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.13 cN / dtex in a water jet loom to obtain a woven fabric.

  The obtained woven fabric was immersed in hot water at 85 ° C. for shrinkage treatment, and then dried at 125 ° C. to obtain an airbag base fabric. The warp tension in the shrinking process was 0.05 cN / dtex.

  When the density of the obtained airbag fabric was measured, the warp density was 51 / 2.54 cm, and the weft density was 51 / 2.54 cm. Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is apparent from Table 1, the obtained airbag fabric was a low-breathable fabric that satisfied the initial restraining performance when the airbag was deployed, and was a very excellent airbag fabric. .

Reference example 2
A polyester fiber (flat single yarn) having a flatness of 2.8 in cross section of single yarn was used as a raw material for the synthetic fiber, and 72 flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 5.3 dtex, the boiling water shrinkage of the multifilament yarn is 6.2%, and the total fineness is 385 dtex.

  The obtained multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.25 cN / dtex in a water jet loom to obtain a woven fabric.

  The obtained woven fabric was immersed in hot water at 98 ° C. for shrinkage treatment, and then dried at 130 ° C. to obtain a base fabric for airbag. The warp tension in the shrinking process was 0.07 cN / dtex.

  When the density of the obtained base fabric for airbag was measured, the warp density was 59 / 2.54 cm, and the weft density was 59 / 2.54 cm. Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is apparent from Table 1, the obtained airbag fabric was a low-breathable fabric that satisfied the initial restraining performance when the airbag was deployed, and was a very excellent airbag fabric. .

Comparative Example 1
Nylon 66 fiber (flat single yarn) with a flatness of 3.3 in the single yarn cross section was used as a raw material for the synthetic fiber, and 96 flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 4.9 dtex, the boiling water shrinkage of the multifilament yarn is 8.5%, and the total fineness is 470 dtex.

  The obtained multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.25 cN / dtex in a water jet loom, and then dried at 120 ° C. to obtain a woven fabric.

  The obtained woven fabric was subjected to shrinkage processing at 180 ° C. using a pin tenter to obtain an airbag base fabric. The warp tension in the shrinking process was 0.12 cN / dtex.

  When the density of the obtained airbag fabric was measured, the warp density was 50 / 2.54 cm, and the weft density was 49 / 2.54 cm. Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is apparent from Table 1, since the warp tension during shrinkage was large, the air bag base fabric had high air permeability.

Comparative Example 2
Nylon 66 fiber (flat single yarn) with a flatness of 3.3 in the single yarn cross section was used as a raw material for the synthetic fiber, and 96 flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 4.9 dtex, the boiling water shrinkage of the multifilament yarn is 8.5%, and the total fineness is 470 dtex.

  The obtained multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.40 cN / dtex in a water jet loom, and then dried at 120 ° C. to obtain a woven fabric.

  The obtained woven fabric was subjected to shrinkage processing at 200 ° C. using a pin tenter to obtain an airbag base fabric. The warp tension in the shrinking process was 0.15 cN / dtex.

  When the density of the obtained airbag fabric was measured, the warp density was 50 / 2.54 cm, and the weft density was 50 / 2.54 cm. Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is apparent from Table 1, although the warp tension at the time of weaving was increased, the tension at the time of shrinkage was large, so that the air bag base fabric had high air permeability.

Comparative Example 3
Nylon 66 fiber (flat single yarn) with a flatness of 3.3 in the single yarn cross section was used as a raw material for the synthetic fiber, and 96 flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 4.9 dtex, the boiling water shrinkage of the multifilament yarn is 3.0%, and the total fineness is 470 dtex.

  The resulting multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.40 cN / dtex in a water jet loom to obtain a woven fabric.

  The obtained woven fabric was immersed in hot water at 95 ° C. for shrinkage treatment, and then dried at 130 ° C. to obtain an airbag base fabric. The warp tension in the shrinking process was 0.06 cN / dtex.

  When the density of the obtained airbag fabric was measured, the warp density was 49 / 2.54 cm, and the weft density was 49 / 2.54 cm. Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is clear from Table 1, despite the fact that the warp tension at the time of weaving was increased, the flat water of the flat single yarn was not aligned due to the low boiling water shrinkage of the multifilament yarn, and the air permeability was high. It was inferior as a base fabric.

Comparative Example 4
A nylon 66 fiber (flat single yarn) having a flatness of 1.0 in cross section of a single yarn was used as a raw material for the synthetic fiber, and 144 such flat single yarns were collected to obtain a multifilament yarn. The fineness of the flat single yarn is 3.3 dtex, the boiling water shrinkage of the multifilament yarn is 8.5%, and the total fineness is 470 dtex.

  The obtained multifilament yarn was woven in a plain weave with a warp tension adjusted to 0.30 cN / dtex in a water jet loom to obtain a woven fabric.

  The obtained woven fabric was immersed in hot water at 95 ° C. for shrinkage treatment, and then dried at 130 ° C. to obtain an airbag base fabric. The warp tension in the shrinking process was 0.06 cN / dtex.

  When the density of the obtained airbag fabric was measured, the warp density was 49 / 2.54 cm, and the weft density was 49 / 2.54 cm. Further, the air permeability of the airbag fabric was measured, and the results are shown in Table 1 below. As is clear from Table 1, the flatness of the flat single yarn was small, so that the air permeability was high and the airbag fabric was inferior.

It is a schematic diagram which shows an example of the cross-sectional shape of the flat single yarn in this invention.

Explanation of symbols

a: major axis b: minor axis

Claims (5)

A method for producing a base fabric for an air bag by weaving a multifilament yarn made of synthetic fibers and subjecting the resulting woven fabric to shrinkage processing,
The multifilament yarn is composed of a single yarn having a flatness of 1.2 to 6, and a boiling water shrinkage of 7 to 15%.
The warp tension when weaving the multifilament yarn is 0.1 cN / dtex to 0.30 cN / dtex,
The shrinking process is performed using hot water of 80 ° C. to 100 ° C., and the warp tension is suppressed to 0.05 cN / dtex or more and 0.08 cN / dtex or less, and the air permeability under a differential pressure of 20 kPa is 0.28 L / cm. The manufacturing method of the base fabric for airbags which obtains the base fabric for airbags of ² / min or less.   The process according to claim 1, wherein polyamide fiber is used as the single yarn. The method according to claim 1 or 2 , wherein the woven fabric obtained by weaving is subjected to shrinkage processing without drying. The manufacturing method in any one of Claims 1-3 including the drying process of 150 degrees C or less after the said shrink processing process. A base fabric for an airbag obtained by the production method according to any one of claims 1 to 4,
An air bag base fabric having an air permeability of 0.28 L / cm ² / min or less under a differential pressure of 20 kPa.