Fabric for air bag and production method thereof

Abstract

The invention relates to fabric for an air bag. The maximum difference rate of dynamic air permeability test results of six positions in the breadth direction of the fabric for the air bag according to ASTM D 6476 test standards is smaller than 12%. The fabric for the air bag is small in physical property deviation in the breadth direction, and therefore the human body protection function of the air bag is improved. The invention further provides a production method of the fabric for the air bag.

Description

Technical Field

[0001] The invention relates to an air bag fabric with small physical property deviation in width direction and a production method thereof. Background Art

[0002] In recent years, with increasing awareness of traffic safety, the effectiveness of airbags has been recognized, and their practical application has rapidly advanced. Following a vehicle collision, airbags inflate and deploy within the vehicle within a very short time, preventing the impact force from moving and absorbing the shock to protect occupants.

[0003] Existing non-adhesive airbag fabrics do not involve how to achieve dynamic air permeability with small deviation, nor do they involve technologies and solutions for reducing physical property differences in the width direction, especially differences in dynamic air permeability at various points. Summary of the Invention

[0004] An object of the present invention is to provide an airbag fabric having small deviation in physical properties in the width direction and a method for producing the same.

[0005] The airbag fabric of the present invention has a maximum difference rate of less than 12% in dynamic air permeability test results at six locations across the width according to the ASTM D 6476 test standard, preferably less than 10%. The dynamic air permeability of non-adhesive fabrics across the width is generally 200 mm / s to 800 mm / s. If the dynamic air permeability is less than 200 mm / s, the impact on the sewing area during airbag explosion is large, which can easily cause the sewing line to slip and lead to airbag damage. If the dynamic air permeability is greater than 800 mm / s, the airbag's air permeability is too high and cannot effectively protect the human body. If the difference between each point is greater than 12%, when used as the main piece for the driver's seat and passenger seat, the fabric will not be used efficiently when cut into airbag bags, and the airbag shape will vary greatly when the airbag explodes, reducing its protective function for the human body.

[0006] The airbag fabric of the present invention has a maximum difference rate of static air permeability test results of 6 positions in the width direction according to ISO 9237 test standard of less than 15%, preferably less than 10%. The static air permeability of non-coated fabric in the width direction is less than 10L / dm 2 / min. If the static air permeability is greater than 10L / dm 2 / min, the airbag's air permeability is too high and it cannot effectively protect the human body. If the difference between these points is greater than 15%, when used as the main panel for the driver's seat and front passenger seat, the fabric will not be fully utilized when cut into airbags. In addition, the airbags will have large variations in shape when deployed, reducing their protective function.

[0007] According to the ISO 13934-1 tensile strength test standard, the airbag fabric of the present invention has a warp tensile strength of 600 N / cm to 900 N / cm at five locations across the width of the fabric, with a maximum difference in test results of less than 5%. The weft tensile strength of the fabric at five locations across the width of the fabric is 600 N / cm to 900 N / cm, with a maximum difference in test results of less than 5%. The difference in test results between the warp elongation at break and the weft elongation at break is less than 10%. If the warp and weft tensile strengths of the fabric are greater than 900 N / cm, high performance requirements are placed on the filaments used in weaving, which will result in increased production costs. If the tensile strength at break of the fabric is less than 500 N / cm, the fabric will easily break when unfolded and will not effectively protect the human body. If the difference between each point is greater than 5%, the tensile strength results for the same fabric will vary greatly, which will inevitably lead to large differences in elongation at break results, resulting in large differences in the airbag's unfolding shape when the airbag explodes and large differences in the airbag's pressure-retaining effect. If the difference between the test results of the warp elongation at break and the weft elongation at break is greater than 10%, the utilization rate of the air bag will decrease during cutting due to the large difference, resulting in increased costs.

[0008] The fabric for airbags of the present invention has a warp tear strength of 120N to 300N at five locations across the width of the fabric according to the ISO 13937-2 tear strength test standard, and the maximum difference in the test results is less than 5%. The weft tear strength of the fabric at five locations across the width of the fabric is 120N to 300N, and the maximum difference in the test results is less than 5%. If the warp and weft tear strengths of the fabric are greater than 300N, high performance requirements are placed on the filaments used in weaving, which will result in an increase in production costs. If the tear strength of the fabric is less than 120N, the fabric cannot withstand the concentrated stress generated by the impact of high-pressure and high-temperature airflow on the airbag during airbag deployment, and cannot provide protection for the human body. If the difference between each point is greater than 5%, when used as the main sheet for the driver's seat and the front passenger seat, especially when cutting airbags with high tear strength requirements, the cutting rate will decrease.

[0009] The maximum difference rate in the present application is as follows: (maximum value - minimum value) / maximum value x 100%.

[0010] The filaments of the airbag fabric of the present invention can be nylon filaments or polyester filaments, and the fineness of the filaments is 350dtex to 700dtex.

[0011] The fabric for airbags of the present invention has a warp and weft needle grip strength of 500N to 900N, as tested according to ASTM D6479-02. If the warp and weft needle grip strengths exceed 900N, the cohesion between the filaments increases, resulting in a hardened surface. Consequently, an airbag formed from this fabric occupies a large space when folded, which is detrimental to the trend toward smaller space requirements. If the warp and weft needle grip strengths are less than 500N, the filaments are likely to slip significantly at the sewn edges when the airbag is exploded, increasing air permeability and rendering the airbag ineffective in providing protection.

[0012] Another object of the present invention is to provide a method for producing airbag fabrics, including warping, weaving, and finishing, which is characterized in that: during weaving, waste yarn is used on the right side of the loom to straighten the weft yarn; during finishing, water washing, pre-drying in a needleless drying room, and heat setting by a roller are used.

[0013] During weaving, waste yarn is used on the right side of the loom to straighten the weft yarn and reduce slack on the right end. After weaving, the waste yarn can be cut off with a hot melt knife. Waste yarn can also be used on the left side. The cut grey fabric proceeds to the next process. Finishing involves water washing, pre-drying in a needleless drying room, and heat setting on a drum, ultimately producing the finished product. Water washing removes the oil added during the spinning process and improves the needle grip of the finished fabric. Pre-drying in a needleless drying room allows the semi-finished product to be evenly set across the width of the fabric on the drum after pre-drying. This allows the grey fabric to fully contact the drum across the width, minimizing uneven heating on the drum caused by slack on the right side of the fabric. Heat setting with a drum is intended to improve the physical property differences between the needle plate and needleless areas of the fabric in traditional needle plate drying ovens, which can occur due to inconsistent shrinkage.

[0014] The pin-free drying room in this application is relative to the traditional pin-plate drying room with a pin plate, and means a drying room without a pin plate.

[0015] The waste yarn is made of nylon 6 or nylon 66 fully stretched yarn, with 2 or 3 strands, a strand fineness of 350dtex to 550dtex, and a twist of 150 twists / m to 300 twists / m. The number of waste yarns is 16 to 32. If the strands are less than 2, the strand fineness is less than 350dtex, the twisting twist is less than 150 twists / m, and the number of waste yarns is less than 16, the waste yarn cannot effectively improve the slack of the cloth edge during weaving, cannot effectively stretch the right end weft yarn, and the slack phenomenon on the right side of the woven grey fabric cannot be effectively improved. If the strands are greater than 3, the strand fineness is greater than 550dtex, the twisting twist is greater than 300 twists / m, and the number of waste yarns is greater than 32, on the one hand, the cost increases, and on the other hand, the waste yarn is stretched too much during weaving, resulting in a large difference in the weaving state of the waste yarn part and the adjacent warp yarn part, an uneven cloth surface, and wrinkles after subsequent rollers. The breaking strength of a single scrap yarn should be greater than 15N, and the elongation at break should be greater than 12%. If the breaking strength of a single scrap yarn is less than 15N and the elongation at break is less than 12%, the scrap yarn is prone to breakage when the weaving tension is too high. The weaving tension for a single scrap yarn should be between 40CN and 80CN. If it is less than 40CN, the right weft yarn cannot be effectively straightened, and the slack at the fabric edge cannot be corrected. If it is greater than 80CN, the scrap yarn will be overstretched, resulting in a significant difference in the weaving state between the scrap yarn and the adjacent warp yarn, an uneven surface, and wrinkles after subsequent rollers. The weft insertion tension for a single weft yarn should be between 40CN and 70CN. If the weft insertion tension for a single weft yarn is less than 40CN, the right weft yarn cannot be effectively straightened, and the slack at the right end cannot be corrected. If the tension is greater than 70CN, the nozzle water pressure must be increased, which will cause weft shrinkage defects in the fabric and damage the weft yarn. After weaving the grey fabric, the scrap yarn should be cut away with a hot melt knife. If the waste yarn is not cut off, the waste yarn will shrink too much during washing, drying and drum setting, causing the fabric surface to be uneven and wrinkles to form.

[0016] The above-mentioned method for producing airbag fabric is characterized by: a water washing temperature of 60°C to 95°C, a washing tank tension of 800N to 1500N, a pre-drying temperature of 90°C to 120°C in a needleless drying room, a drum temperature of 110°C to 150°C, and a speed of 25m / min to 35m / min. If the water washing temperature is less than 60°C, the amount of oil added during the spinning process cannot be reduced, and the friction between the filaments decreases, resulting in a decrease in the needle grip strength of the fabric. If the water washing temperature is greater than 95°C, the washing tank is prone to scale contamination. Furthermore, since the grey fabric removes some water from the washing tank, it is difficult to maintain a balanced temperature within the tank during rehydration and subsequent steam heating. Two washing tanks are generally used, but one or more can also be used. When using two washing tanks, the tension in tank #1 should be 600N to 1200N, and in tank #2 should be 800N to 1500N, with a tension difference of 200N to 300N between the two. If the tension in tank #1 is less than 600N, the tension in tank #2 is less than 800N, or the tension difference between the two tanks is less than 200N, the fabric will not be effectively stretched during the washing process, resulting in low weft elongation. If the tension in tank #1 is greater than 1200N, the tension in tank #2 is greater than 1500N, or the tension difference between the two tanks is greater than 300N, the fabric will wrinkle. If the pre-drying temperature of the needle-free drying room is less than 90°C and the drum temperature is less than 110°C, on the one hand, the fabric will not be fully shaped and will have poor dimensional stability; on the other hand, the fabric will not be able to fully shrink in the weft direction and will have large differences in physical properties in the warp and weft directions; if the pre-drying temperature of the needle-free drying room is greater than 120°C and the drum temperature is greater than 150°C, the fabric will be overheated and easily softened, and the dynamic and static air permeabilities will be too high. The airbag will not be able to deploy in time when it explodes and will not play a role in protecting the human body. The length of the grey cloth passing through the drying room is 20m to 30m, and 8 drums are used. The temperature of the 8 drums can be the same or can increase gradually from front to back. The tensile force on the grey cloth on the drum of this application is controlled by superheated steam, and the steam pressure range is 0.25MPa to 0.65MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The specific positions of the six positions for width direction testing are shown. DETAILED DESCRIPTION

[0018] The present invention is described in more detail by the following examples and comparative examples. The physical properties in the examples are measured by the following methods.

[0019] Dynamic breathability:

[0020] According to ASTM D 6476 test standard, 400cm 3 Pressure vessel, test pressure 30kPa~70kPa, peak pressure 100±5kPa, test head area 100cm2 The test positions are as follows: the first test position is 300mm away from one side of the fabric edge; the second test point is at the same weft position as the first test point and 200mm away from the first test point; the third and fourth test positions are 200mm away from the first and second test positions in the warp direction and in the middle of the fabric, 100mm away from the middle position respectively; the sixth test position is 300mm away from the other side of the fabric edge and 200mm away from the third and fourth test points in the warp direction; the fifth test point is at the same weft position as the sixth test point and 200mm away from the sixth test point.

[0021] Static air permeability:

[0022] According to ISO 9237 test standard, test pressure 500Pa, test head area 100cm 2 The test positions are as follows: the first test position is 300mm away from one side of the fabric edge; the second test point is at the same weft position as the first test point and 200mm away from the first test point; the third and fourth test positions are 200mm away from the first and second test positions in the warp direction and in the middle of the fabric, 100mm away from the middle position respectively; the sixth test position is 300mm away from the other side of the fabric edge and 200mm away from the third and fourth test points in the warp direction; the fifth test point is at the same weft position as the sixth test point and 200mm away from the sixth test point.

[0023] Tensile Strength and Elongation:

[0024] Testing is conducted according to ISO 13934-1, the standard for tensile strength testing. Specifically, a 5cm x 30cm specimen is clamped to a dedicated tensile strength tester with a 20cm gap between the jaws. Testing is performed at a speed of 20cm / min. Sampling is performed at five locations, 20cm from each end of the fabric, along the remaining fabric.

[0025] Tearing strength:

[0026] Tear strength testing is performed according to ISO 13937-2. Specifically, a 20cm x 15cm specimen is clamped to a dedicated tear strength tester with a 10cm gap between the jaws. Testing is performed at a speed of 10cm / min. Sampling is performed at five locations, 20cm from each end of the fabric, along the remaining fabric.

[0027] Needle grip strength:

[0028] Testing was conducted according to ASTM D6479-02. The specific method was to place a 5cm x 30cm sample on a dedicated needle grip strength tester with the upper and lower jaws 20cm apart and the upper jaw moving at a speed of 20cm / min. Sampling was performed at five locations, 20cm from each end of the fabric, along the remaining surface.

[0029] Example 1

[0030] The airbag fabric is made of nylon 66 yarn with a total fineness of 355 dtex, 136 filaments, and a circular cross-section. Its tensile strength at break is 30.5 N, and its elongation at break is 20.5%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is 26 strands of nylon 6, 350 dtex, twisted with three fully drawn strands to a twist of 150 twists / m. The fabric is then processed in a needleless drying room at 70°C (No. 1) and 80°C (No. 2). The fabric is then washed and heat-set in a 22-meter-long, needleless drying room at 120°C (No. 3), with eight rollers each at 130°C (No. 4), at a speed of 30 m / min. The resulting fabric has a warp density of 59 yarns / inch and a weft density of 59 yarns / inch. The fabric's properties are evaluated and shown in Table 1.

[0031] Example 2

[0032] The airbag fabric is made of nylon 66 yarn with a total fineness of 476 dtex, 136 filaments, and a circular cross-section. Its tensile strength at break is 40.0 N, and its elongation at break is 20.4%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is 18 strands of nylon 6, 470 dtex, twisted with three fully drawn strands to a twist of 150 twists / m. The fabric is then processed in a needleless drying room at 100°C, 120°C on all eight rollers, and 25 m in length. The resulting fabric has a warp density of 53 strands / inch and a weft density of 53 strands / inch. The fabric's properties are evaluated and shown in Table 1.

[0033] Example 3

[0034] The airbag fabric is made of nylon 66 yarn with a total fineness of 717 dtex, 108 filaments, and a circular cross-section. Its tensile strength at break is 59.0 N, and its elongation at break is 20.3%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is 16 strands of nylon 66, 550 dtex, twisted with two fully drawn strands at a twist of 300 twists / m. The fabric is then washed in the No. 1 washing tank at 60°C and the No. 2 washing tank at 80°C. The fabric is then post-processed in a 28-meter-long, needle-free drying room at 120°C, with eight rollers each at 140°C, at a speed of 35 m / min. The resulting fabric has a warp density of 41 strands / inch and a weft density of 41 strands / inch. The fabric's properties are evaluated and shown in Table 1.

[0035] Example 4

[0036] The airbag fabric is made of 568 dtex polyester yarn with 144 filaments and a circular cross-section. Its tensile strength at break is 46.1 N, and its elongation at break is 22.4%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is 22 strands of 470 dtex nylon 66, twisted with two fully drawn strands at a twist of 300 twists / m. The fabric is then processed in a needleless drying room at 110°C, 130°C for the first washing tank, and 30 m / min for the eighth drying drum. The resulting fabric has a warp density of 51 strands / inch and a weft density of 51 strands / inch. The fabric's properties are evaluated and shown in Table 1.

[0037] Comparative Example 1

[0038] The airbag fabric is made of nylon 66 yarn with a total fineness of 355 dtex, 136 filaments, and a circular cross-section. Its tensile strength at break is 30.5 N, and its elongation at break is 20.5%. The loom is a Toyota 810 water jet loom. No waste yarn is used on the right side. The fabric was then post-processed in a needleless drying room at 120°C, 130°C for 22 m, and 130°C for 8 drums at a speed of 30 m / min. The resulting fabric has a warp density of 59 yarns / inch and a weft density of 59 yarns / inch. The fabric's properties are evaluated and shown in Table 2.

[0039] Comparative Example 2

[0040] The airbag fabric is made of nylon 66 yarn with a total fineness of 476 dtex, 136 filaments, and a circular cross-section. Its tensile strength at break is 40.0 N, and its elongation at break is 20.4%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is 18 strands of nylon 6, 470 dtex, twisted with three fully drawn strands to a twist of 150 twists / m. The fabric is then processed in a needleless drying room at 80°C (no. 1) and 50°C (no. 2). The fabric then passes through a 25-meter-long washing and heat-setting machine at a speed of 33 m / min, with eight rollers at 160°C each and a needleless drying room temperature of 80°C. The resulting fabric has a warp density of 53 strands / inch and a weft density of 53 strands / inch. The fabric's properties are evaluated and shown in Table 2.

[0041] Comparative Example 3

[0042] The airbag fabric is made of nylon 66 yarn with a total fineness of 476 dtex, 136 filaments, and a circular cross-section. Its tensile strength at break is 40.0 N, and its elongation at break is 20.4%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is made of 12 strands of nylon 6, 470 dtex, twisted with one fully drawn strand at a twist of 50 twists / m. The fabric is then processed in a needleless drying room at 100°C, 120°C on all eight rollers, and 33 m / min. The resulting fabric has a warp density of 53 strands / inch and a weft density of 53 strands / inch. The fabric's properties are evaluated and shown in Table 2.

[0043] Comparative Example 4

[0044] The airbag fabric is made of nylon 66 yarn with a total fineness of 717 dtex, 108 filaments, and a circular cross-section. Its tensile strength at break is 59.0 N, and its elongation at break is 20.3%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is 16 strands of nylon 66, 550 dtex, twisted with three fully drawn strands at a twist of 200 twists / m. The fabric was then post-processed in a needleless drying room at 60°C (No. 1) and 80°C (No. 2). The fabric was then washed and heat-set in a 28-meter-long, needleless drying room at 80°C, with eight rollers each at 100°C and a speed of 35 m / min. The resulting fabric has a warp density of 41 strands / inch and a weft density of 41 strands / inch. The fabric's properties are evaluated and shown in Table 2.

[0045] Comparative Example 5

[0046] The airbag fabric is made of nylon 66 yarn with a total fineness of 717 dtex, 108 filaments, and a circular cross-section. Its tensile strength at break is 59.0 N, and its elongation at break is 20.3%. The loom is a Toyota 810 water jet loom. No waste yarn is used on the right side. The fabric was post-processed in a washing and heat-setting machine with a speed of 35 m / min. The temperatures in the No. 1 and No. 2 washing tanks were set at 60°C and 80°C, respectively. The fabric was then dried in eight sections with needle plates, all at 140°C with an overfeed of 2%. The width of the first drying section was 250 cm, the widths of the second to seventh sections were 238 cm, and the width of the eighth section was 235 cm. The fabric had a warp density of 41 yarns / inch and a weft density of 41 yarns / inch. The fabric's properties were evaluated and are shown in Table 2.

[0047] Comparative Example 6

[0048] The airbag fabric is made of 568 dtex polyester yarn with 144 filaments and a circular cross-section. Its tensile strength at break is 46.1 N, and its elongation at break is 22.4%. The loom is a Toyota 810 water jet loom. The right-side waste yarn is 32 strands of 470 dtex nylon 66, twisted with four fully drawn yarns at a twist of 400 twists / m. The fabric was then post-processed in a needleless drying room at 110°C, 130°C for eight rollers, and 25 m in length. The resulting fabric has a warp density of 51 strands / inch and a weft density of 51 strands / inch. The fabric's properties are evaluated and shown in Table 2.

[0049] Table 1

[0050]

[0051]

[0052] Table 2

[0053]

[0054]

Claims

1. A fabric for an airbag, characterized in that : According to the ASTM D 6476 test standard, the maximum difference rate of the dynamic air permeability test results at 6 positions in the width direction is less than 12%, among which Maximum difference rate = (maximum value - minimum value) / maximum value × 100%.

2. The airbag fabric according to claim 1, wherein : According to ISO 9237 test standard, the maximum difference rate of static air permeability test results at 6 positions in the width direction is less than 15%, among which Maximum difference rate = (maximum value - minimum value) / maximum value × 100%.

3. The airbag fabric according to claim 1, wherein: According to the ISO 13934-1 tensile strength test standard, the warp tensile strength of the fabric at 5 locations across the width is 600N / cm to 900N / cm, with a maximum difference of less than 5% in the test results; the weft tensile strength of the fabric at 5 locations across the width is 600N / cm to 900N / cm, with a maximum difference of less than 5% in the test results; the difference between the warp elongation at break and the weft elongation at break test results is less than 10%, where Maximum difference rate = (maximum value - minimum value) / maximum value × 100%.

4. The airbag fabric according to claim 1, wherein: According to the ISO 13937-2 tear strength test standard, the tear strength of the warp direction of the fabric at 5 locations across the width is 120N to 300N, and the maximum difference in the test results is less than 5%; the tear strength of the weft direction of the fabric at 5 locations across the width is 120N to 300N, and the maximum difference in the test results is less than 5%, where Maximum difference rate = (maximum value - minimum value) / maximum value × 100%.

5. The airbag fabric according to claim 1, wherein: The fineness of the warp and weft filaments of the fabric is 350 dtex to 700 dtex.

6. The airbag fabric according to claim 1, wherein: According to the test standard of ASTM D6479-02, the warp and weft needle grip strength of the fabric is 400N to 900N.

7. A method for producing the airbag fabric according to claim 1, comprising warping, weaving and finishing, wherein: During weaving, waste yarn is used on the right side of the loom to straighten the weft yarn; during finishing, water washing, pre-drying in a needleless drying room, and heat setting by rollers are used.

8. The method for producing an airbag fabric according to claim 7, wherein : The waste yarn is made of nylon 6 or nylon 66, and the fully stretched yarn is twisted with 2 to 3 strands, the twist is 100 twists / m to 300 twists / m, the fineness is 350dtex to 550dtex, the number of waste yarns is 16 to 32, and the weft insertion tension of a single weft yarn is 40CN to 70CN; after weaving into the grey cloth, the waste yarn is cut off with a hot melt knife.

9. The method for producing an airbag fabric according to claim 7, wherein : The water washing temperature is 60-95°C, the washing tank tension is 600N-1500N; the pre-drying temperature of the needle-free plate drying room is 90-120°C; the drum temperature is 110-150°C.

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