Airbag fabric and method of manufacturing the same

Abstract

In conventional weaving methods, the tension of warp yarns at width-direction end parts during weaving tends to be insufficient, and as a result, a difference in crimp ratio between the width-direction center and the width-direction end parts of the base fabric has been generated. The difference in crimp ratio has caused unevenness in the width direction of a woven fabric. As a solution thereto, in the present invention, the boiling water shrinkage percentage of to-be-inserted additional yarns is set to be lower than that of foundation yarns, so that shrinkage is suppressed in the width-direction end parts of the base fabric, resulting in making it possible to decrease the difference in crimp ratio between the width-direction center and the width-direction end parts of the base fabric, thereby making it possible to produce an airbag base fabric having excellent evenness in the width direction.

Description

[Technical Field]

[0001] The present invention relates to an airbag fabric and a method for manufacturing an airbag fabric. [Background technology]

[0002] Airbags are installed in automobiles to protect the occupants by inflating instantly with high-temperature, high-pressure gas during a collision in an automobile accident. To withstand the instantaneous inflation caused by high-temperature, high-pressure gas during a collision, airbag fabrics must be highly tenacious and have low breathability.

[0003] To weave a high-strength, low-breathability airbag fabric, high-strength yarn is used to weave at a high density, and in many cases, the finished green fabric is subjected to refining and shrinkage to further increase the density after weaving, resulting in a high-quality fabric. Hereinafter, the refining and shrinking base fabric will be referred to as the airbag base fabric.

[0004] Conventional airbag fabrics, which are high-density woven fabrics, have flare (also called loose selvedge) at their widthwise edges. The flare is a defect at the widthwise edge of the fabric, and can cause other defects such as selvedge height and wrinkles when the fabric is rolled up. The flare occurs because the crimp rate (the shrinkage of the woven yarn, which appears wavy when viewed in cross section) of the warp yarns that make up the airbag fabric differs between the widthwise center and the widthwise edges of the fabric.

[0005] During the cutting process, multiple sheets are usually stacked and the widthwise edges, which are prone to selvedge tassels and other defects that occur during weaving, are cut. As the flare increases, the amount of material that needs to be cut increases, resulting in greater loss. In addition, there is a limit to the height of the cutter's inlet, and after stacking, the widthwise edges become too bulky to fit through the inlet. As a result, the number of stacked sheets that can be cut at one time decreases, resulting in poor work efficiency. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2014-181430 A Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 1 specifies the desirable boiling water shrinkage rate for the yarns that make up the woven fabric, but does not describe a technology for improving the uniformity of the fabric by adding yarns with different boiling water shrinkage rates, and the uniformity between the center and end warps in the width direction of the base fabric is insufficient.The present invention is a technology that uses a specific additional yarn with a boiling water shrinkage rate different from that of the ground yarns that make up the airbag base fabric, reducing the difference in crimp rate between the center warp yarn in the width direction and the warp yarns at the end warps in the width direction, thereby improving the uniformity of the fabric. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that the above problems can be solved by the following means, and have thus completed the present invention. That is, the present invention is as follows. (1) In an airbag fabric having selvedge tassels at the widthwise ends of the fabric, at least two or more additional yarns are included at each of the widthwise ends, The crimp rate of the warp yarns arranged in the center of the base fabric width direction is in the range of 7 to 20%. The crimp rate of the warp yarns arranged at both ends in the width direction of the base fabric is 3 to 15% or less, and the difference in crimp rate between the warp yarns arranged at both ends and the warp yarns arranged in the center is 5.0% or less. (2) The airbag fabric according to (1), wherein the boiling water shrinkage rate of the additional yarn is smaller than the boiling water shrinkage rate of the ground yarn constituting the airbag fabric, and the difference is 0.8% or more. (3) A method for manufacturing an airbag base fabric according to (1), characterized in that an additional yarn is used in which the boiling water shrinkage rate of the base yarn is greater than that of the additional yarn, and the difference in boiling water shrinkage rate between the base yarn and the additional yarn is 0.8% or more, at least two additional yarns are included at each end of the width direction of the base fabric, and scouring shrinkage is performed. [Effects of the Invention]

[0009] By including additional yarns characterized by a difference in boiling water shrinkage rate between the ground yarn and the additional yarns (ground yarn boiling water shrinkage rate > additional yarn boiling water shrinkage rate), even if the ground yarn tries to shrink in boiling water, the shrinkage rate of the adjacent additional yarns is smaller than that of the ground yarn, so deformation of the widthwise ends of the base fabric due to shrinkage is suppressed, and the change in crimp of the warp yarns arranged at the widthwise ends is reduced, maintaining the crimp rate at the same level as that of the widthwise center of the base fabric, resulting in reduced flare. DETAILED DESCRIPTION OF THE INVENTION

[0010] The airbag fabric of the present invention is a woven fabric made of synthetic multifilament fibers. The total fineness of the synthetic fiber multifilaments constituting the airbag fabric is preferably 200 to 600 dtex, more preferably 300 to 550 dtex. If the total fineness is 200 dtex or more, there is no need to increase the weaving density excessively, which prevents an excessive increase in the binding force between the warp and weft yarns and makes it easier to keep the storability in the airbag module within an appropriate range. Furthermore, if the total fineness is 600 dtex or less, it is easier to prevent an excessive increase in the rigidity of the woven yarns themselves. Furthermore, if the synthetic fiber multifilaments have a total fineness of 200 to 600 dtex, the fabric is moderately flexible, which makes it easier to obtain an airbag fabric that has good storability in the module, and is therefore preferred.

[0011] In the present invention, the total fineness of the synthetic multifilament fiber constituting the airbag fabric is determined as follows. The warp and weft yarns of the fabric obtained through the dry finishing process are separately unwoven, and the total fineness is measured in accordance with JIS L1013 (2010) 8.3.1. Specifically, an initial load is applied, a sample exactly 90 cm long is taken, the bone dry mass is measured, and the corrected fineness (dtex) is calculated using the following formula, and the average of five measurements is taken as the total fineness. F0 = 10000 × m / 0.9 × (100 + R0) / 100 F0: Positive fineness (dtex) m: Absolute dry mass of sample (g) R0: Official moisture content (%)

[0012] The airbag fabric of the present invention is woven with ground yarns (warp and weft yarns constituting the airbag fabric) and further includes additional yarns having specific physical properties. The boiling water shrinkage rate of the additional yarns is preferably smaller than that of the ground yarns constituting the airbag fabric, and in particular, it is preferable that the boiling water shrinkage rate of the additional yarns is smaller than that of the ground yarns (warp).

[0013] In order to suppress flare due to shrinkage at the widthwise edges of the base fabric during scouring and drying, the difference in boiling water shrinkage rate between the ground yarn and the additional yarn is preferably 0.8 to 20%, more preferably 1.5 to 15%, and particularly preferably 4 to 12%. If it is less than 0.8%, the effect of suppressing deformation due to shrinkage is small, and if it exceeds 20%, the ground yarn shrinks too much, causing the weave to collapse and adversely affecting strength, breathability, etc.

[0014] The boiling water shrinkage rate of the ground yarn and the additional yarn used in the airbag fabric of the present invention may be greater than that of the ground yarn, but it is more effective if the difference is 0.8% or more. The additional yarn may be a multifilament yarn, a monofilament yarn, or a false-twisted or crimped yarn, and its material may be nylon 66 fiber, nylon 6 fiber, polyester fiber, or the like. Nylon 66 fiber is generally used as the ground yarn of airbag fabrics, and since polyester fiber has a lower boiling water shrinkage rate than nylon 66 fiber, it is preferable to use nylon 66 fiber for the ground yarn and polyester fiber for the additional yarn.

[0015] In the present invention, the weave density is measured in accordance with JIS L1096 (2010) 8.6.1. Specifically, the sample is placed on a flat table and unnatural wrinkles and tension are removed, then the number of warp and weft threads in 2.54 cm sections at five different locations is counted, and the average value for each unit length is calculated to determine the weave density.

[0016] In the present invention, the boiling water shrinkage of the raw yarn was measured in accordance with JIS L1013 (2010) Hot water dimensional change rate, filament dimensional change rate (method B). Specifically, it was measured as follows. An initial load is applied to the sample, two points 500 mm apart are marked, the initial load is then removed, and the sample is immersed in hot water at 100°C for 30 minutes. The sample is then removed and lightly wiped dry with absorbent paper or cloth, air-dried, and the initial load is applied again. The length between the two points is measured, and the hot water dimensional change rate (%) is calculated using the following formula, and the average of three measurements is taken as the boiling water shrinkage rate. ΔL = (L - 500) / 500 × 100 ΔL: Boiling water shrinkage rate (%) L: Length between two points (mm)

[0017] The material of the synthetic fiber multifilament constituting the airbag fabric of the present invention is not particularly limited and can be selected from a wide range. In order to satisfy the above-mentioned properties while taking into consideration economic efficiency, multifilaments made of polyamide resins such as nylon 6, nylon 66, and nylon 46, and polyester resins mainly composed of polyethylene terephthalate are preferred.

[0018] The synthetic fiber multifilament constituting the airbag fabric of the present invention may contain various additives that are commonly used in the yarn manufacturing process or the fabric manufacturing process to improve productivity or properties. The synthetic fiber multifilament constituting the airbag fabric of the present invention may contain, for example, at least one selected from the group consisting of a heat stabilizer, an antioxidant, a light stabilizer, a smoothing agent, an antistatic agent, a plasticizer, a thickener, a pigment, and a flame retardant.

[0019] Although the number of additional yarns in the airbag fabric of the present invention is not particularly limited, the effect tends to improve as the number increases. Considering operability, etc., 2 to 12 yarns are preferable, but since there are differences depending on the manufacturing equipment, there is no problem with inserting any number as long as it does not impair operability and quality.

[0020] The width of the airbag fabric of the present invention is not particularly limited, but the wider the width, the more likely flare will occur. It is useful when the width is 160 cm or more, and particularly useful when the width is 180 cm or more.

[0021] The flare-reducing technology of the present invention is particularly effective in high-density woven fabrics. The cover factor of the airbag fabric of the present invention is preferably 1800 to 2600, and more preferably 2000 to 2500. The CF was calculated using the following formula: CF = (A × 0.9) 1 / 2 ×(W1)+(B×0.9) 1 / 2 ×(W2) In the formula, A and B indicate the thickness (dtex) of the warp and weft yarns, and W1 and W2 indicate the warp density and weft density (lines / 2.54 cm).

[0022] The woven fabric of the airbag fabric of the present invention may be plain weave, twill weave, satin weave, or modified weaves thereof, but is not limited to any particular weave.

[0023] In the airbag fabric of the present invention, by inserting multiple additional yarns (ground yarn > additional yarn) with a boiling water shrinkage rate difference of 0.8% or more with the ground yarn in the selvage portions, in the airbag fabric with selvage tassels remaining at the widthwise ends of the base fabric, the difference in crimp rate between the warp yarns arranged in the widthwise center of the base fabric and the warp yarns arranged at the widthwise ends of the base fabric is 5.0% or less, thereby improving flare.

[0024] Furthermore, the airbag fabric of the present invention can be further coated with a silicone resin or the like as necessary to further improve its low breathability, and can also be used effectively as a coated airbag fabric. [Example]

[0025] The configuration and effects of the present invention will be described in detail below using examples.

[0026] <Crimping rate measurement> Measurement was carried out according to the method described in JIS L-1096 8.7 Method B. Ten samples were taken from the widthwise center of the base fabric, and 10 samples from each of the left and right ends of the base fabric were taken from the widthwise extreme ends of the base fabric, excluding the additional yarns, and the average values ​​for the widthwise center and widthwise ends of the base fabric were calculated. The difference in crimp rate between the right and left width ends of the base fabric and the widthwise center of the base fabric was used as the larger value.

[0027] <Weave density of base fabric> Measurements were made according to JIS L1096 (2010) 8.6.1. The sample was placed on a flat table, and after removing any unnatural wrinkles or tension, the number of warp and weft threads in a 2.54 cm section was counted to determine the density. Measurements were made at 5 cm intervals from the base of the selvedge tassel, with n = 35 or more. Both warp and weft densities were measured, and the difference was calculated for each measurement point.

[0028] Example 1 Nylon 66 filament raw yarn (monofilament cross section is round) with a fineness of 470 dtex / 144f and a boiling water shrinkage rate of 8.4% was used in the warp and warp directions of the base yarn, and a water jet loom was used to add two additional yarns with a boiling water shrinkage rate of 0.3% at each end (a total of four) to achieve a weave density of 53.0 threads / 2.54 cm in both warp and weft directions, and the fabric was woven in a plain weave.The fabric was then passed through a hot water shrinkage bath at 98°C without drying, and then passed through a drying finishing process using a two-stage suction drum dryer, with the temperature T1 of the first stage controlled at 130°C and the temperature T2 of the second stage controlled at 135°C.

[0029] Example 2 Nylon 66 filament raw yarn (monofilament cross section is round) with a fineness of 470 dtex / 144f and a boiling water shrinkage rate of 8.4% was used in the warp and warp directions of the base yarn, and a water jet loom was used to add 10 additional yarns with a boiling water shrinkage rate of 0.3% to each end (total of 20) to achieve a weave density of 53.0 threads / 2.54 cm in both warp and weft directions, and the fabric was woven in a plain weave.The fabric was then passed through a hot water shrinkage bath at 98°C without drying, and then passed through a drying finishing process using a two-stage suction drum dryer, with the temperature T1 of the first stage controlled at 130°C and the temperature T2 of the second stage controlled at 135°C.

[0030] Example 3 Nylon 66 filament raw yarn (monofilament cross section is round) with a fineness of 470 dtex / 144f and a boiling water shrinkage rate of 8.4% was used in the warp and warp directions of the base yarn, and a water jet loom was used to weave a plain weave with 10 additional yarns at each end (total of 20) with a boiling water shrinkage rate of 6.8% so that the weave density was 53.0 threads / 2.54 cm in both warp and weft directions.The fabric was then passed through a hot water shrinkage bath at 98°C without drying, and then passed through a drying finishing process using a two-stage suction drum dryer, with the temperature T1 of the first stage controlled at 130°C and the temperature T2 of the second stage controlled at 135°C.

[0031] (Comparative Example 1) Nylon 66 filament raw yarn (monofilament cross section is round) with a fineness of 470 dtex / 144f and a boiling water shrinkage rate of 8.4% in the warp and warp directions of the ground yarn was woven in a plain weave using a water jet loom to achieve a weave density of 53.0 threads / 2.54 cm in both warp and weft directions. After that, without drying, the fabric was passed through a hot water shrinkage bath at 98°C, and then passed through a drying finishing process using a two-stage suction drum dryer, with the temperature T1 of the first stage controlled at 130°C and the temperature T2 of the second stage controlled at 135°C.

[0032] [Table 1] [Industrial Applicability]

[0033] According to the present invention, the quality of the airbag base fabric can be improved by reducing the difference in crimp rate between the center and end portions in the width direction of the base fabric, which contributes to cost reduction in the airbag manufacturing industry.

Claims

1. In an airbag base fabric having selvedge tassels remaining at the widthwise end of the base fabric, At least two or more additional yarns are included at each of both ends in the width direction, The crimp rate of the warp yarns is in the range of 7 to 20% as an average value measured by JIS L-1096 8.7 B method on 10 yarns taken from the center of the base fabric width direction, Ten ground yarns are taken from each of the left and right ends of the airbag fabric in the width direction at the outermost ends in the width direction, excluding the additional yarns, and the average crimp rate of the warp yarns is measured according to JIS L-1096 8.7 B method, and is 3 to 15% or less; The difference in crimp rate between the warp yarns arranged at both ends and the warp yarns arranged at the center is 5.0% or less, The boiling water shrinkage rate of the additional yarn is The boiling water shrinkage rate is smaller than that of the ground yarn that constitutes the airbag base fabric, The additional yarn is made of at least one material selected from the group consisting of nylon 66, nylon 6, and polyester fiber, The airbag fabric, wherein the ground yarn is made of at least one material selected from the group consisting of nylon 66, nylon 6, and polyester fiber.

2. A method for manufacturing an airbag base fabric as described in claim 1, characterized in that an additional yarn is used in which the boiling water shrinkage rate of the base yarn is greater than the boiling water shrinkage rate of the additional yarn, and the difference in boiling water shrinkage rate between the base yarn and the additional yarn is 0.8% or more, at least two additional yarns are included at each end of the base fabric width direction, and scouring shrinkage is performed.

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