Synthetic fiber for air bag and method for manufacturing woven fabric for air bag using the same

Abstract

Provided is a synthetic fiber for air bags that can be suitably used in both warp and weft when a woven fabric for air bags is woven using a WJL. A synthetic fiber for air bags, a take-up package of the synthetic fiber for air bags, a method for manufacturing the package, and a method for manufacturing a woven fabric for air bags using the synthetic fiber for air bags as weft, the synthetic fiber for air bags being characterized by being a multifilament synthetic fiber for air bags having an interwoven portion and a non-interwoven portion, a water droplet contact angle of a single yarn surface being 50 to 75°, and a deviation in the area of the non-interwoven portion per 20 cm being 10% or less in terms of a CV value.

Description

Technical Field

[0001] This invention relates to synthetic fibers for airbags and a method for manufacturing woven fabrics for airbags using the same. Background Technology

[0002] Airbags were developed to protect passengers in the event of a car collision. Airbags protect passengers by inflating a cushion with high-pressure gas generated by an inflator after a collision is detected. For reliable passenger protection, the airbag cushion needs to be maintained inflated for an extended period; in other words, internal pressure retention is required. In recent years, remote curtain airbags to prevent collisions between the driver and front passenger, and pedestrian airbags to protect pedestrians, have emerged. However, these require storage in confined spaces such as seats and hoods, further necessitating a more compact airbag cushion design.

[0003] The manufacturing process of airbag cushions mainly consists of four steps: spinning, weaving, sewing, and assembly. In the weaving step, a water jet loom (WJL) is frequently used. The WJL sprays water obliquely from the side onto the yarn entering from behind the nozzle, causing the yarn to be guided by the water jet. The weft yarns, guided at the warp opening, are then controlled on the opposite side of the nozzle and beaten to form the woven fabric.

[0004] In recent years, efforts have been made to increase the weaving speed, improve the efficiency of the process, and reduce labor intensity in the weaving process based on WJL to improve productivity.

[0005] In Patent Document 1 below, the weft yarn is allowed to fly stably and reliably by limiting the diffusion of water ejected from the weft insertion nozzle, thereby improving weaving efficiency. On the other hand, depending on the type of yarn, if the weaving speed is increased, insufficient flight may sometimes occur during weft insertion, resulting in weaving failures.

[0006] To address this problem, Patent Document 2 discloses a synthetic fiber for airbags obtained by interlacing in a manner that improves the flight properties of the weft yarns during weaving. This enables high-speed weaving at 850 rpm to 1000 rpm, reducing the drawbacks of the process. However, it only mentions the number of weaving stops and does not describe the quality of the woven fabric.

[0007] In addition, in the following patent document 3, by increasing the intermediate load elastic modulus of the synthetic fiber, reducing the intermediate elastic elongation, improving the responsiveness to high-speed weft insertion, and suppressing the deviation of the intermediate load elastic modulus, the woven fabric obtained by high-speed weaving at 900 rpm also achieves uniform air permeability.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2000-34646

[0011] Patent Document 2: Japanese Patent Application Publication No. 2007-126796

[0012] Patent Document 3: Japanese Patent No. 5253685 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] As described above, existing technologies achieve uniform air permeability in woven fabrics even at high speeds by improving the responsiveness to forces on the weft yarn in the flight direction and suppressing deviations in the yarn length direction of the responsiveness. The air permeability of a woven fabric is a parameter related to air leakage occurring on the fabric surface, which affects the internal pressure retention of the air bladder. However, during air bladder deployment, air leakage occurring at the seams is more severe than air leakage occurring on the fabric surface, and the impact of the fabric's air permeability on internal pressure retention is negligible.

[0015] The parameter related to air leakage at the sewn part of the woven fabric is slip resistance. If the slip resistance is high, the sewn part will not easily shift due to stress when the airbag deploys, and the internal pressure will not easily decrease.

[0016] On the other hand, stiffness is a parameter related to the airbag's retractability within the vehicle. The airbag cushion is folded and stored inside the vehicle as an airbag device; if the stiffness is high, the folded volume will be larger, making it impossible to store it fully.

[0017] To improve slip resistance, methods such as increasing weaving density and shrinkage rate are commonly used, but these methods can compromise the softness of the woven fabric. Therefore, there is an urgent need for airbag woven fabrics that offer both high slip resistance and high softness, and an urgent need for airbag yarns that can achieve both properties.

[0018] In this context, the problem to be solved by the present invention is to provide a synthetic fiber for airbags that is suitable for use in both warp and weft yarns when using woven fabrics for airbags with WJL. In particular, it provides a synthetic fiber for airbags that reduces tension unevenness when the weft yarn flies at high speed and reaches the opposite side of the nozzle, provides uniformity in the tracking of the sprayed water, and suppresses quality deviations in the width direction of the woven fabric when flying at high speed (because the instantaneous elastic recovery of the polyamide yarn stabilizes in the width direction of the woven fabric before it is woven), enabling the woven fabric to achieve both high slip resistance and high softness, which are mutually exclusive.

[0019] Solution for solving the problem

[0020] The inventors unexpectedly discovered that in the weaving of the aforementioned woven fabrics using WJL, the uniformity of the non-interlaced area is important for the uniform flight of the yarn, and the instantaneous hydrophilicity of the yarn is important for its ability to follow jet water, thus completing the present invention.

[0021] That is, the present invention is as follows.

[0022] [1] A synthetic fiber for airbags, characterized in that it is a multifilament synthetic fiber for airbags having interlaced and non-interlaced portions, the water droplet contact angle on the surface of the single yarn is 50 to 75°, and the deviation of the non-interlaced portion area per 20 cm is less than 10% in terms of CV value.

[0023] [2] According to the synthetic fiber for airbags described in [1] above, the area of ​​the aforementioned non-interlaced portion is 12.5 to 20 cm² in every 20 cm along the yarn length direction. 2 The range.

[0024] [3] The synthetic fiber for airbags described in [1] or [2] above has a single yarn count of 60 to 250.

[0025] [4] The synthetic fiber for airbags according to any one of [1] to [3] above has a single yarn fineness of 1 to 7 dtex.

[0026] [5] The synthetic fiber for airbags according to any one of [1] to [4] above has a single yarn count of 200 to 250 and a single yarn fineness of 1.0 dtex to 1.8 dtex.

[0027] [6] The synthetic fiber for airbags according to any one of [1] to [5] above has a weave density of 10 to 35 strands / m.

[0028] [7] The synthetic fiber for airbags according to any one of [1] to [6] above, wherein the deviation of the water droplet contact angle on the surface of the single yarn in the length direction is less than 5% in terms of CV value.

[0029] [8] The synthetic fiber for airbags according to any one of [1] to [7] above has a finishing agent adhesion rate of 0.6 to 1.2% by weight.

[0030] [9] The synthetic fiber for airbags according to any one of [1] to [8] above, wherein an anionic surfactant containing phosphorus atoms and / or an anionic surfactant containing sulfur atoms are attached at 200 to 500 ppm relative to the fiber weight.

[0031]

[10] The synthetic fiber for airbags according to any one of [1] to [9] above satisfies the following conditions (1) to (4):

[0032] (1) Total fineness is 150-800 dtex;

[0033] (2) Strength is 7.5–9 cN / dtex;

[0034] (3) Elongation rate is 15-25%; and

[0035] (4) The shrinkage rate of boiling water is 4-11%.

[0036]

[11] The airbag synthetic fiber roll-up package according to any one of [1] to

[10] above, wherein the width W of the package is 8 to 22 cm.

[0037]

[12] A method for manufacturing synthetic fibers for airbags, characterized in that it includes the following steps:

[0038] The process of taking synthetic fibers spun by melt spinning onto a tube using a take-up machine equipped with a traverse mechanism for rocking the yarn along the tube axis, via one or more finishing agent supply (oiling) devices, multi-segment stretching rollers, interlacing supply devices, and one or more yarn path control guides provided before and after the interlacing supply devices.

[0039] The tension before winding in this process is 0.1 to 0.3 cN, and the short-cycle oscillation amplitude ratio B of the yarn oscillation based on the traverse mechanism is 0.5 to 5%.

[0040]

[13] In the method for manufacturing synthetic fibers for airbags described above

[12] , the width W of the package obtained by winding the synthetic fibers into a tube is 8 to 22 cm.

[0041]

[14] The method for manufacturing synthetic fibers for airbags according to

[12] or

[13] above, wherein the finishing agent is applied by means of an anionic surfactant containing phosphorus atoms and / or an anionic surfactant containing sulfur atoms, with an amount of 200 to 500 ppm relative to the weight of the fiber, using the aforementioned finishing agent application device.

[0042]

[15] In the method for manufacturing synthetic fiber for airbags according to any one of

[12] to

[14] above, there are two or more finishing agent applicators at different positions in the yarn path direction, and the oil supply sections of at least two finishing agent applicators face each other.

[0043]

[16] A method for manufacturing a woven fabric for an airbag, comprising the following steps:

[0044] In a water jet loom, the weft yarn is made of the synthetic fiber for airbags described in any one of the above [1] to

[10] , and the woven fabric is manufactured at a weaving speed of 800 rpm or more.

[0045] The effects of the invention

[0046] The synthetic fiber for airbags of the present invention significantly improves weft yarn flight (following of water jets) during weaving using WJL by setting the deviation of water droplet contact angle and non-interlaced area on the surface of the single yarn within a specific range, and also exhibits excellent uniform and straight flight characteristics (uniform yarn flight). Due to these two characteristics, there is no quality deviation in the width direction of the base fabric, enabling high-speed weaving. Attached Figure Description

[0047] Figure 1 This is a diagram illustrating the width W of the synthetic fiber roll-up packaging for airbags.

[0048] Figure 2 This is a diagram illustrating an example of an apparatus for manufacturing synthetic fibers for airbags.

[0049] Figure 3 This is a diagram illustrating the definition of the short-cycle oscillation amplitude ratio B and the lead angle θ at the start of winding, which are used to determine the speed increase / decrease of the traverse in the winding machine.

[0050] Figure 4 This is an explanatory diagram for measuring the contact angle of a water droplet.

[0051] Figure 5 This is an explanatory diagram illustrating the definitions of the length a and width b of the non-interlaced portion used to calculate the area and CV value of the non-interlaced portion. Detailed Implementation

[0052] The embodiments of the present invention will be described in detail below.

[0053] One embodiment of the present invention is a synthetic fiber for airbags, characterized in that it is a multifilament synthetic fiber for airbags having interlaced and non-interlaced portions, the water droplet contact angle on the surface of the single yarn is 50 to 75°, and the deviation of the non-interlaced portion area per 20 cm is less than 10% in terms of CV value.

[0054] In this embodiment, the water droplet contact angle on the surface of the synthetic fiber monoyarn used for the airbag is 50° or more and 75° or less. Water droplet contact angle refers to: (e.g., ...) Figure 4 As shown, a certain amount of water droplets adhere to the single yarn of the synthetic fiber used in the airbag. When the contact angle is observed from the side, the maximum contact angle value is displayed within 100ms (one frame of the video is 8ms).

[0055] If the water droplet contact angle is greater than 50°, the surface tension of the water jet during weft insertion plays a moderate role within the yarn, allowing the yarn to fly without loosening. Because the yarn doesn't loosen, air resistance during flight is reduced, improving weft flight and stabilizing weft insertion at high speeds. Due to this stabilized weft insertion behavior, the weft yarn is woven into the warp yarn after instantaneous elastic recovery, thus contributing to the uniformity of fabric properties in high-speed weaving. Furthermore, the uniform water jet content within the yarn results in uniform flight, further contributing to the uniformity of fabric properties. Conversely, if the contact angle is less than 75°, the yarn's hydrophilicity increases, improving its ability to follow the water jet. This prevents problems such as nozzle formation (water jet explosion), water scattering, and the yarn failing to reach the opposite side of the nozzle, leading to insufficient flight and weaving defects. By making the water droplet contact angle low, the sprayed water inclusion of the yarn occurs rapidly within milliseconds. Therefore, the expansion of the non-interlaced portions occurs quickly, and the flight properties of the sprayed water become efficient. For the same reasons mentioned above, this contributes to the homogenization of the woven fabric properties. The lower the water droplet contact angle α, the more homogenized the properties of the airbag base fabric. A water droplet contact angle is more preferably 50–70°, and even more preferably 50–65°.

[0056] In this embodiment, the deviation of the water droplet contact angle along the yarn length of the synthetic fiber monofilament surface used for the airbag is 5% or less, expressed as a coefficient of variation (CV). If the CV is 5% or less, the finishing agent adheres uniformly to the monofilament along the yarn length, resulting in uniform water content in the yarn during weft insertion. This reduces the deviation in flight performance and decreases the deviation in the ratio of slip resistance to stiffness (EC / V). In other words, a woven fabric with uniform quality can be obtained, particularly a woven fabric with uniform quality in the width direction of the base fabric. The CV value is preferably 4.5% or less. The lower limit of the CV value is not particularly limited; it can be 1% or more, as it is economically achievable.

[0057] In this embodiment, the deviation of the non-interlaced area per 20 cm of synthetic fiber used for the airbag is calculated using a CV value (variance factor) of 10% or less. If the CV value is 10% or less, then... Figure 5As shown, when the length 'a' of the non-interlaced portion and the yarn extension width 'b' based on the surface tension of the finishing agent are uniform, the water content in the yarn becomes uniform during weft insertion when weaving using WJL, the deviation in flight properties disappears, and the deviation in the ratio of slip resistance to stiffness (EC / V) can be reduced. In other words, a woven fabric with uniform quality can be obtained, especially a woven fabric with uniform quality in the width direction of the base fabric. The CV value is preferably 8% or less, more preferably 7% or less. The lower limit of the CV value is not particularly limited, and it can be 3% or more as a range that can be economically achieved. In the measurement of a 20cm yarn length, if the non-interlaced portion is uniform regardless of where it is measured, the flight property based on the water jet becomes uniform.

[0058] In this embodiment, the area of ​​the non-interlaced portion of the synthetic fiber used for the airbag is preferably 12.5 to 20 cm² per 20 cm along the yarn length. 2 If the area of ​​the non-interlaced portion is 12.5 cm² 2 In this way, the yarn fully contains water, the weft yarn has good flight properties, and the loom can be prevented from stopping. On the other hand, if the area of ​​the non-interlacing part is 20cm² 2 The following allows for the appropriate length of the interlacing section, preventing the yarn from becoming loose and thus avoiding loom stoppages. In an evaluation of the non-interlacing section area, 14–17.5 cm per 20 cm along the yarn length is more preferable. 2 .

[0059] In this embodiment, the synthetic fiber for the airbag preferably contains 200 to 500 ppm of anionic surfactants containing phosphorus atoms and / or anionic surfactants containing sulfur atoms relative to the fiber weight. By containing 200 ppm or more of ionic surfactants, the water droplet contact angle is sufficiently reduced, the yarn becomes more hydrophilic, and the weft yarn's ability to follow water jets is improved during weft insertion in the weaving process, thus enhancing weft yarn flight. On the other hand, if the adhesion rate is below 500 ppm, the situation of excessively small water droplet contact angle and loose yarn during weft yarn flight in weaving will not occur. The adhesion rate of the anionic surfactant relative to the fiber weight is more preferably 250 to 500 ppm, and more preferably 300 to 500 ppm. The anionic surfactant containing phosphorus atoms is not particularly limited, and examples include, for instance, metal salts or amine salts of alkyl phosphates (hereinafter abbreviated as phosphates), and metal salts or amine salts of polyoxyethylene alkyl phosphates. More specifically, examples include potassium lauryl phosphate, sodium lauryl phosphate, potassium octyl phosphate, and sodium octyl phosphate. Anionic surfactants containing sulfur atoms are not particularly limited; examples include alkane sulfonates. The method of attachment of ionic surfactants is not particularly limited, but it is preferable to mix them into a finishing agent for attachment.

[0060] In this embodiment, the interlacing degree of the synthetic fibers used for the airbag is... Figure 5 In the water immersion method as shown, the interlacing degree is preferably 10 to 35 interlacings / m. If the interlacing degree is 10 interlacings / m or more, the required bundle density of the warp yarns during weaving is sufficiently satisfied, without leading to a decrease in weaving efficiency or damage to the quality of the woven fabric. On the other hand, if the interlacing degree is 35 interlacings / m or less, the area of ​​the non-interlaced portion becomes appropriately sized, the flight of the weft yarn becomes good, and the deviation of the single yarn length in the yarn length direction is small, which can suppress the occurrence of yarn breakage and burrs during weaving and prevent loom stoppage. The interlacing degree is more preferably 15 to 30 interlacings / m.

[0061] In this embodiment, the synthetic fiber used for the airbag is multifilament, and the number of single yarns is preferably 60 to 250. If the number of single yarns is 60 or more, there are sufficient yarns to form the interlacing, and the situation of being unable to form an interlacing or being loose will not occur. The number of single yarns is more preferably 120 or more. On the other hand, if the number of single yarns is 250 or less, the utilization efficiency of the air energy used to impart interlacing is good, and a uniform and good interlacing can be produced. The number of single yarns is more preferably 200 or less.

[0062] The yarn fineness of the multifilament synthetic fiber used for the airbag in this embodiment is preferably 1 to 7 dtex. If the yarn fineness is 1 dtex or more, the tensile properties such as yarn toughness are sufficient, and fuzzing during the yarn manufacturing process can be suppressed. On the other hand, if the yarn fineness is 7 dtex or less, the yarn rotation during the interlacing process can be performed with less energy, and the desired interlacing state can be obtained. Furthermore, if it is 4 dtex or less, the gaps between the yarns are reduced, and therefore, the effect of the surface tension of the water jet in the yarn during weft insertion is increased, allowing the yarn to fly further without loosening. From the viewpoint of obtaining sufficient tensile properties, the yarn fineness is more preferably 2 to 7 dtex, and from the viewpoint of flight performance during weft insertion, the yarn fineness is more preferably 1 to 4 dtex, more preferably 1 to 3 dtex, and even more preferably 1.0 dtex or more and 1.8 dtex or less.

[0063] In this embodiment, the multifilament synthetic fiber used for the airbag preferably has 200 to 250 yarns per strand, and the yarn fineness is 1.0 dtex or more and 1.8 dtex or less. If the yarn fineness is 1.0 dtex or more and 1.8 dtex or less, it provides further softness when made into a woven fabric. If the yarn count is 200 to 250, even with a low yarn fineness of 1.0 dtex or more and 1.8 dtex or less, it possesses sufficient mechanical properties for a multifilament fiber.

[0064] The multifilament synthetic fiber for airbags in this embodiment is expected to have physical properties of a total fineness of 150 to 800 dtex, a strength of 7.5 to 9 cN / dtex, an elongation of 15 to 25%, and a boiling water shrinkage of 4 to 11%.

[0065] If the total fineness is 150 dtex or higher, sufficient mechanical properties are obtained when manufacturing woven fabrics for airbags. On the other hand, if the total fineness is 800 dtex or lower, it is easy to impart bundled properties during the weaving process. In other words, if the fineness increases, the air pressure or airflow required for yarn rotation needs to be significantly increased to impart a proper weaving. This not only increases the cost of the auxiliary materials but also makes the yarn at the weaving nozzle area more susceptible to damage and burrs, leading to a decrease in yarn quality. This does not occur if the total fineness is 800 dtex or lower. A total fineness of 200 to 550 dtex is more preferable.

[0066] The tensile strength is preferably 7.5 to 9.0 cN / dtex. A tensile strength higher than 7.5 cN / dtex helps improve the mechanical properties of the woven fabric. A tensile strength of 8.0 cN / dtex or higher is more preferable. However, considering other properties and manufacturing costs, the tensile strength of the synthetic fibers used in airbags is practically 9.0 cN / dtex or less.

[0067] The elongation is preferably 15-25%. If the elongation is 15% or more, there is no risk of failure due to excessive stress at the boundary between the expanded and non-expanded portions during unfolding. Furthermore, elongation and strength are inversely related; to achieve a balance with strength, the elongation is preferably 25% or less.

[0068] The boiling water shrinkage rate is preferably in the range of 4% to 11%. If the boiling water shrinkage rate is 4% or higher, the woven fabric can be shrunk in the post-weaving processing steps, which helps to achieve high density in the finishing of the woven fabric. The boiling water shrinkage rate is further preferably 6% or higher. If the boiling water shrinkage rate is 6% or higher, the woven fabric can be shrunk in the post-weaving processing steps, which helps to homogenize the deviation of the mechanical properties of the woven fabric. The boiling water shrinkage rate is particularly preferably 7% or higher. If the boiling water shrinkage rate is 11% or lower, when the woven fabric is made, the warp and weft imbalance caused by excessive shrinkage will not occur, thus preventing the formation of mesh defects. The boiling water shrinkage rate is more preferably 9.5% or lower, and even more preferably 9% or lower.

[0069] Another embodiment of the present invention is the aforementioned rolled packaging body of synthetic fibers for airbags, wherein the width W of the packaging body is 8 to 22 cm.

[0070] This type of packaged material (a fibrous packaging form of an object obtained by winding fibers into a paper tube, etc., using a winding machine) is as follows: Figure 1As shown, the width W of the packaging body is preferably 8 to 22 cm. If W is 8 cm or more, the shape is stable and the transportation efficiency is also good. On the other hand, if the width W is 22 cm or less, the variation in the area of ​​the non-interlaced portion is reduced due to the tension difference between the center and both ends of the packaging body in the width direction during winding. W is more preferably 8 to 18 cm.

[0071] The synthetic fibers constituting the airbag synthetic fibers of this embodiment are preferably long fibers formed from polyamide and polyester multifilaments. Polyamide fibers are particularly preferred because they have excellent heat resistance due to their high melting point and large heat capacity. Examples include fibers formed from polyamide 6, polyamide 6 / 6, polyamide 11, polyamide 12, polyamide 6 / 10, polyamide 6 / 12, polyamide 4 / 6, copolymers thereof, and mixtures thereof. Among these, polyamide 6 / 6 fibers formed mainly from polyhexamethylene adipamide fibers are preferred. Polyhexamethylene adipamide refers to polyamide fibers with a melting point of 250°C or higher, composed of 100% hexamethylenediamine and adipic acid. The polyamide 6 / 6 fibers of the present invention can be fibers formed from polymers obtained by copolymerizing or blending polyhexamethylene adipamide with polyamide 8, polyamide 6.1, polyamide 10, polyamide 6 / T, etc., within a melting point range of not less than 250°C.

[0072] Another embodiment of the present invention is a method for manufacturing synthetic fibers for airbags, characterized by comprising the following steps:

[0073] The process of taking synthetic fibers spun by melt spinning onto a tube using a take-up machine equipped with a traverse mechanism that causes the yarn to rock along the tube axis, via one or more finishing agent supply (oiling) devices, multi-segment stretching rollers, interlacing supply devices, and one or more yarn path control guides provided before and after the interlacing supply devices.

[0074] The tension before winding in this process is 0.1 to 0.3 cN, and the short-cycle oscillation amplitude ratio B of the yarn oscillation based on the traverse mechanism is 0.5 to 5%.

[0075] The following describes a method for manufacturing a rolled-up packaging body of synthetic fibers for airbags according to this embodiment.

[0076] Figure 2This is an explanatory diagram showing an example of the equipment used to manufacture the synthetic fiber for the airbag according to this embodiment. First, the molten polymer is homogenized using a part of a spinning machine called a spinneret 3 and spun out from the spinning tube head 4. The spun polymer is solidified using cold air from the cooling chamber 5 to form a yarn. Then, after applying a finishing agent to the yarn wound around each end using an oil supply device 6, it is advanced to a stretching process based on a roller group consisting of a traction roller 7 and first rollers 8 to fourth rollers 11. That is, after the yarn is drawn at a predetermined speed using roller 7, it is introduced into the first section roller 8 with a small tension, and from the first section roller 8, it is stretched using multiple sections of heated stretching rollers 9, 10, and 11. Then, it is supplied to the weaving device 13 via the yarn path control guide 12, and then wound up using a take-up machine 14 via the yarn path control guide 12.

[0077] The oil supply device 6 is typically of the roller or nozzle type. It is acceptable to have one or more oil supply devices 6, preferably two or more at different positions along the yarn path, with at least two of these oil supply units facing each other. Especially when the yarn fineness is 1.0 to 1.8 dtex, there is a tendency for the yarn's movement during the curing process using cold air from the cooling chamber 5 to be transmitted to the oil supply process, causing disordered contact between the yarn and the oil supply device 6, resulting in uneven adhesion of the finishing agent. By having two or more oil supply devices at different positions along the yarn path, and ensuring that at least two of these oil supply units face each other, disordered contact between the yarn and the oil supply device can be suppressed. Therefore, even with a yarn fineness of 1.0 to 1.8 dtex, the finishing agent can be evenly adhered, and deviations in the yarn length direction of the water droplet contact angle on the yarn surface can be suppressed.

[0078] The adhesion rate of the finishing agent applied to the synthetic fibers by the oil supply device 6 is preferably in the range of 0.6 to 1.2% by weight. Yarns with an adhesion rate of less than 1.2% by weight will hardly cause the weft yarn to have difficulty flying due to stickiness. If the adhesion rate of the finishing agent is 0.6% by weight or more, the occurrence of single yarn burrs during the stretching process in the yarn making process can be suppressed.

[0079] From the perspective of yarn quality and industrial material applications, in addition to the aforementioned ionic surfactants, the finishing agent applied to the synthetic fibers by the oil supply device 6 preferably contains components with excellent smoothness and heat resistance in order to smoothly stretch the yarn in the yarn-making process.

[0080] The component of the smoothing agent is preferably an ester compound. It preferably includes at least one ester compound selected from ester compounds having three or more ester bonds in their molecules and ester compounds containing sulfur in their molecules.

[0081] Ester compounds containing sulfur in their molecules include, for example, (1) ester compounds of dicarboxylic acids and monohydric alcohols such as dialkyl thiopropionate, and (2) ester compounds of monocarboxylic acids and monohydric alcohols such as alkyl mercaptopropionate.

[0082] Examples of ester compounds having three or more ester bonds in their molecules include (3) ester compounds of polyols and monocarboxylic acids such as trimethylolpropane trialkylate, triglyceride tricarboxylic acid ester, pentaerythritol tetracarboxylic acid ester, and trimethylolpropane fatty acid ester; (4) ester compounds of polycarboxylic acids and monocarboxylic acids such as trimellitic acid trialkyl ester and triethyl citrate; and (5) natural oils such as castor oil, palm oil, and refined rapeseed oil. These components can be used individually or in combination of two or more.

[0083] Nonionic surfactants can be used as modifiers for emulsification and friction.

[0084] Examples include (1) ether ester compounds obtained by condensing at least one compound selected from polyethylene glycol dialkylates, polyoxyethylene dehydrated sorbitol monoalkylates, polyoxybutylene dehydrated sorbitol trialkylates, polyoxypropylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene propylene hydrogenated castor oil trialkylates, polyoxyethylene hydrogenated castor oil trialkylates, ethylene oxide (hereinafter referred to as EO) adducts of castor oil, and EO adducts of hydrogenated castor oil with monocarboxylic acids and dicarboxylic acids; (2) nonionic surfactants of polyoxyalkylene polyol fatty acid ester type, such as those containing organic acids, organic alcohols, organic amines, and organic acids. Compounds obtained by adding at least one of the organic amides to an epoxide alkane with 2 to 4 carbon atoms, more specifically, such as ether-type nonionic surfactants like polyoxyethylene fatty acid esters, polyoxyethylene fatty acid ester methyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene polyoxypropylene nonylphenyl ethers, polyoxyethylene alkyl amino ethers, and polyoxyethylene fatty acid amide ethers; (3) polyol partial ester-type nonionic surfactants like dehydrated sorbitol monofatty acid esters, dehydrated sorbitol trifatty acid esters, and glycerol monofatty acid esters; (4) alkylamide-type nonionic surfactants like diethanolamine monofatty acid amides. These components can be used alone or in combination of two or more.

[0085] Finishing agents can be diluted with mineral oil or other similar substances, or they can be formulated into water-based emulsions. While there are no particular limitations, it is preferable to use them as emulsions, considering their compatibility with water in subsequent processes.

[0086] Upstream and downstream of the interlacing device 13, yarn path control guides 12 are provided to stabilize the yarn path. Maintaining the yarn path angle, defined by these guides and the interlacing nozzle of the interlacing device, within a range of 1 to 10° is preferred for obtaining synthetic fibers for airbags with minimal deviation. Setting the interval between the two yarn path control guides 12 to 50 to 90 mm is preferred for obtaining a suitable non-interlacing area. The interlacing device 13 can use a known device that injects compressed fluid into the yarn using an interlacing nozzle, and the compressed fluid injected into the yarn is preferably supplied with an energy of 0.5 to 3.5 kW. The energy supplied with the compressed fluid can be determined based on the supply pressure (MPa) and the usage flow rate (Nm³). 3 The above-mentioned energy supply range can be satisfied by calculating the product of the supply pressure and the fluid inlet diameter of the interlacing nozzle by arbitrarily selecting the supply pressure and the fluid inlet diameter of the interlacing nozzle. Furthermore, it is preferable to adjust the speed ratio between the fourth roller 11 and the winding machine, and adjust the temperature of the fourth roller 11 within the above-mentioned range, setting the winding tension (pre-winding tension) between the fourth roller 11 and the winding machine 14 to a range of 0.1 to 0.3 cN / dtex. If the winding tension is 0.1 cN or more, yarn will not fall off, and the shape of the package will be stable. In addition, the density of the package increases, and the transportation efficiency becomes higher. On the other hand, if the pre-winding tension is 0.3 cN or less, interlacing is fully engaged, the deviation of the interlacing section is reduced, and the tension variation when unpacking the package can be minimized, resulting in excellent unpacking properties of the package.

[0087] In this embodiment, the synthetic fibers for the airbag are wound onto a paper tube or the like using a winding machine 14. At this time, the yarn oscillates axially on the paper tube due to the traversing mechanism, swinging left and right within the width of the packaged body, and is packaged into a cylindrical shape. If the angle between the winding direction of the interlaced fiber yarn on the cylinder and the plane perpendicular to the rotation axis of the packaged body cylinder is set as the guide angle θ, then (interlacing speed) = (winding speed) × (tanθ), and the interlacing speed is controlled by setting the guide angle. When controlling the interlacing speed, the speed of the left and right swinging within the winding width is preferably achieved by using a short-cycle swinging method with a short-cycle swinging amplitude ratio B of 0.5 to 5% based on the set guide angle.

[0088] Short-period oscillation amplitude ratio B Figure 3B is defined as follows. It can be set in applications involving the control of the traverse mechanism. The guide angle θ typically changes with the winding time. By setting B, a fine guide angle change can be applied for a specific winding time. For example, if the guide angle at the start of take-up is 10°, setting B to 1% allows for a short-periodic guide angle change of -0.1 to 0.1° (±1% of 10°) to the time-varying guide angle. Here, "short period" refers to a period of 0.1 to 2 seconds. B is set to prevent ribbon roll-up. The inventors have discovered that by performing this variable interlacing, the take-up tension variation of the yarn caused by interlacing can be suppressed, without damaging the weaving, resulting in uniform synthetic fibers for airbags with small deviations in the non-interlaced area. If the short-period oscillation amplitude ratio B is set to 0.5% or more, ribbon roll-up can be avoided, and take-up tension variation can be suppressed. On the other hand, if B is set to 5% or less, there is no issue of take-up diameter deviation or yarn shedding due to the size of the guide angle within the short period.

[0089] Another embodiment of the present invention is a method for manufacturing a woven fabric for an airbag, comprising the following steps:

[0090] In a water jet loom, the weft yarn uses the aforementioned synthetic fiber for airbags, and the fabric is woven at a weaving speed of 800 rpm or higher.

[0091] In order to obtain synthetic fibers for airbags with good flight performance in WJL, the improvement of interlacing uniformity achieved by adjusting the interlacing conditions and the improvement of yarn hydrophilicity achieved by selecting finishing agents are particularly important.

[0092] The synthetic fiber for airbags of this embodiment is suitable for use as weft yarn in WJL-based weaving, especially high-speed weaving at 800 rpm or higher, and weaving on wide looms of 2 m or more. The synthetic fiber for airbags of this embodiment can also be suitable as warp yarn in weaving. Furthermore, the warp yarn can be sizing treated to improve smoothness before weaving. Additionally, oil can be removed by a scouring process after weaving, or the scouring process can be omitted. The woven fabric can be shrunk by treating it with warm water or hot air. This shrinkage process can be used to control tension or adjust the rate of dimensional change in the width and roll length directions of the woven fabric.

[0093] The synthetic fiber for airbags in this embodiment is suitable for weaving into high-density woven fabrics using yarns, preferably with a fabric cover factor of 2000 to 2500. A fabric cover factor of 2000 or higher ensures sufficient strength and low air permeability for use as an airbag woven fabric. Conversely, a fabric cover factor of 2500 or lower maintains sufficient softness, thinness, and lightweight. A fabric cover factor of 2200 to 2500 is more preferred. Furthermore, the fabric cover factor is defined as {warp density (threads / 2.54cm) × (warp fineness (dtex))}. 1 / 2 +Weft density (threads / 2.54cm) × (Weft fineness (dtex)) 1 / 2}

[0094] The ratio of slip resistance to stiffness (EC / V) of the woven fabric for airbags obtained using the synthetic fibers of this embodiment is preferably 25 N / N or more. If the EC / V is 25 N / N or more, a woven fabric with sufficient low air permeability and softness for use as an airbag is formed. The EC / V is more preferably 35 N / N or more, and even more preferably 45 N / N or more.

[0095] The deviation of the ratio of slip resistance to stiffness (EC / V) of the airbag woven fabric obtained using the synthetic fibers of this embodiment is preferably 20% or less in terms of CV value. If the CV value of EC / V is 20% or less, an airbag woven fabric with less deviation in the width direction, stable base fabric properties, high slip resistance, and good softness is formed. Therefore, even if the airbag components are cut from any part of the woven fabric, they will have the same properties, and the reliability of the airbag is improved. The CV value of EC / V is more preferably 17.5% or less, and even more preferably 15% or less.

[0096] Example

[0097] The present invention will be specifically described below with examples and comparative examples, but the present invention is not limited to these examples. Furthermore, in the specification, the composition, property definitions, and measurement methods of the finishing agents used in the following examples are as follows.

[0098] (1) Preparation of finishing agent

[0099] The finishing agent used in spinning oils is formulated using the following method.

[0100] First, we create the basic component A. The components of component A are as follows.

[0101] Dialkyl (C12-18) thiodipropionate: 40 parts by weight

[0102] • 25 molar adduct of hydrogenated castor oil in ethylene oxide: 30 parts by weight

[0103] • Propylene oxide / ethylene oxide alkyl (C12-18) polyether: 30 parts by weight

[0104] An alkyl (C12-16) phosphate ammonium salt, which serves as an ionic surfactant, was added to component A of the above-mentioned base in such a manner as described in Tables 1 and 2 below, to prepare a finishing agent. Water was added to make the finishing agent content 22% by weight to prepare an emulsion.

[0105] (2) Water droplet contact angle (°)

[0106] The water droplet contact angle was measured using an automated minimum contact angle meter (MCA-J, manufactured by Kyowa Interface Science Co., Ltd.). Figure 4 This is an explanatory diagram for measuring the water droplet contact angle. As part of the measurement conditions, in an indoor atmosphere with an air temperature of 25°C and humidity of 50%, a single yarn is fixed between measuring fixtures, and 20 μL of water at 24°C is placed on the yarn. The water droplet's condition is captured on video from the side using a camera, and the contact angle α is measured. The contact angle α decreases over time (as water gradually seeps into the yarn). To confirm the instantaneous water fusion of the yarn, the maximum contact angle within 100 ms (one frame of video is 8 ms) is taken as the measured value. This operation is repeated using other single yarns, and the average of five measurements is taken as the water droplet contact angle of each single yarn relative to the water.

[0107] (3) The coefficient of variation of the water droplet contact angle along the yarn length direction (CV)

[0108] Regarding the water droplet contact angle, for a single yarn, 10 points are measured every 5cm, and the CV value of the single yarn is calculated using the following methods.

[0109] CV(%) = (s / X) × 100

[0110] Here, s is the standard deviation and X is the mean.

[0111] This operation is repeated using five other single yarns, and the average CV value of each single yarn is used as the variation coefficient CV of the water droplet contact angle along the yarn length. The higher the CV value, the greater the deviation.

[0112] (4) Interlacing degree (numbers / m)

[0113] The interlacing degree test was performed using a water bath 1.2m long, 20cm wide, and 15cm deep. White lines were placed at 10cm intervals from each end, or in other words, at 1m intervals. Water supplied from the inlet was drained from the bath via overflow. The water in the test bath was continuously replenished by supplying fresh water at a rate of approximately 500cc / minute. In the test method, the ends of a 1.2m-long strip of yarn were held and immersed in the test bath under a tension of approximately 10cN. The number of interlacings (interlacings / m) between the white lines when the yarn was relaxed at the water surface was visually recorded. These measurements were repeated 50 times, and the average value was evaluated.

[0114] (5) Area of ​​non-interlaced portion (cm²) 2 )

[0115] Similar to (4) above, the yarn strip is immersed in the test bath, as follows: Figure 5 As shown, the length 'a' and width 'b' of the non-interlaced portion of the yarn spreading on the water surface are measured using a ruler, and 'a×b' is taken as the area of ​​the non-interlaced portion. Within a 20cm area of ​​yarn length, the areas of the non-interlaced portions spreading on the water surface are summed, and this is considered one measurement. This measurement is performed for a different 20cm area each time, and repeated 25 times to obtain the average value.

[0116] (6) The coefficient of variation (CV) of the area of ​​the non-interlaced part

[0117] The area of ​​the non-interlaced portion measured in (5) above is calculated as follows. The higher the CV value, the greater the deviation.

[0118] CV(%) = (s / X) × 100

[0119] Here, s is the standard deviation and X is the mean.

[0120] (7) Fineness

[0121] The measurements were performed according to JIS L 1017 8.3a. Additionally, a length measuring machine with a frame circumference of 1.25 m was used to measure 50 m of the sample from the rolled-up package.

[0122] (8) Strength (cN / dtex), elongation (%)

[0123] After the specimens were placed under standard conditions (20°C, 65%) for 12 hours, the measurements were performed according to JIS L 1017 8.5a. Additionally, the measurements were performed under conditions of a specimen length of 250 mm and a tensile speed of 300 mm / min.

[0124] (9) Boiling water shrinkage rate (%)

[0125] The determination was performed according to JIS L 1017 8.14. Additionally, after immersion in boiling water, the sample was placed indoors under standard conditions (20°C, 65%) for 12 hours.

[0126] (10) Finishing agent adhesion rate (weight %)

[0127] The determination was performed according to JIS L 1017 8.16b. Cyclohexane was used as the extraction solvent.

[0128] (11) Adhesion rate of ionic surfactants (ppm)

[0129] The values ​​(adhesion rate of finishing agent (weight %)) measured in (10) above and the concentration of ionic surfactant in the finishing agent (content of ionic surfactant in finishing agent (%)) are used to calculate the value.

[0130] (12) Weft slippage resistance EC(N)

[0131] The process of taking samples at 5 locations along the width of the base fabric is performed 5 times along the length of the base fabric, in other words, a total of 25 samples are taken. Their weft slip resistance (N) is measured according to ASTM D6479, and their average value is calculated.

[0132] (13) Stiffness of the base fabric V(N)

[0133] In the above (12) weft slip resistance EC test, samples were taken from adjacent parts of the sample, and the base fabric stiffness (N) of 25 samples obtained according to ASTM D4032 was calculated as the average value.

[0134] [Example 1]

[0135] use Figure 2 The apparatus shown melts nylon 66 polymer with a relative viscosity of 80% formic acid, obtained by a conventional polymerization method, at 300°C. The melt is then homogenized using a spinneret 3, spun out through a spinning tube head 4 with 136 orifices, and wound using a direct spinning and stretching process to produce polyamide 66 fibers with a length of 470 dtex and 136 filaments. Specifically, after the spun nylon 66 polymer is cooled and solidified in a cold air chamber 5 to form a yarn, it passes sequentially through an oil supply device 6, a traction roller 7, and first rollers 8 through 4 rollers 11. After the yarn is stabilized using a yarn path control guide 12, an interlacing device 13 interlacs the yarn, allowing it to pass through the yarn path control guide 12 and be wound by a winding machine 14.

[0136] In the oiling process, a finishing agent is applied using a finishing agent applicator with an adhesion rate of 0.7% and an ionic surfactant adhesion rate of 350 ppm. The compressed air supplied to the interlacing applicator 13 is set to 0.5 MPa, and the air supply energy is set to 1.2 kW. The distance between the yarn path control guides 12 is set to 7.3 cm. The winding tension is adjusted to 0.19 cN / dtex. Regarding the winding conditions, the short-cycle oscillation amplitude ratio B is set to 4.0%, the winding start angle is set to 7.8°, and the package width W is set to 16 cm. The physical properties of the resulting polyamide 66 fibers are shown in Table 1 below.

[0137] The obtained polyamide 66 fibers were woven in plain weave using WJL at 900 rpm to obtain a woven fabric. The resulting woven fabric was then scourted continuously at 80°C, and heat-set using a tenter frame at 170°C under conditions of 4% overfeed and 1% width reduction, resulting in a woven fabric with a warp and weft yarn density of 53 × 53 yarns per 2.54 cm. The fabric cover factor was 2298. The slip resistance and base fabric stiffness of the woven fabric were evaluated. The evaluation results are shown in Table 1 below. An appropriate water droplet contact angle resulted in a woven fabric with a small coefficient of variation in non-woven area, a small coefficient of variation in EC / V, and minimal deviation.

[0138] [Example 2]

[0139] In the oiling process, the adhesion rate of the ionic surfactant was set to 490 ppm, and otherwise carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabrics are shown in Table 1 below. The woven fabrics with an appropriate water droplet contact angle, small EC / V variation coefficient, and small deviation are produced.

[0140] [Example 3]

[0141] In the oiling process, the adhesion rate of the ionic surfactant was set to 210 ppm, and otherwise carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 1 below. The water droplet contact angle was appropriate but slightly larger, resulting in a woven fabric with a slightly larger and slightly deviated EC / V variation coefficient.

[0142] [Example 4]

[0143] In the oiling process, the adhesion rate of the ionic surfactant was set to 490 ppm. In the winding process, the package width W was set to 8.5 cm. Otherwise, the process was carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 1 below. The water droplet contact angle was set to an appropriate level, resulting in a woven fabric with a small coefficient of variation in the non-interlaced area, a small coefficient of variation in EC / V, and a small deviation.

[0144] [Example 5]

[0145] In the winding process, the short-cycle shaking amplitude ratio B was set to 1.5%, and the package width W was set to 8.5 cm. Otherwise, the process was carried out in the same manner as in Example 1. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 1 below. A woven fabric with a small coefficient of variation in non-interlaced area, a small coefficient of variation in EC / V, and a small deviation was formed.

[0146] [Example 6]

[0147] In the winding process, the short-cycle oscillation amplitude ratio B was set to 0.8%, and the package width W was set to 8.5 cm. Otherwise, the process was carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 1 below. A woven fabric with a slightly larger coefficient of variation in the non-interlaced area, a slightly larger coefficient of variation in EC / V, and a slight deviation was formed.

[0148] [Example 7]

[0149] In the winding process, the package width W was set to 19.0 cm, and otherwise performed in the same manner as in Example 1. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 1 below. A woven fabric with a slightly large coefficient of variation in the non-interlaced area and a slightly large coefficient of variation in EC / V was formed.

[0150] [Example 8]

[0151] In the interlacing process, the distance between the yarn guides 12 was set to 7.8 cm, and otherwise performed in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 1 below. A woven fabric with a large non-interlaced area, a small EC / V variation coefficient, and a small deviation was formed.

[0152] [Example 9]

[0153] In the interlacing process, the air supply energy was set to 0.7 kW, and otherwise performed in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 2 below. A woven fabric with a large non-interlaced area, a small coefficient of variation of EC / V, and a small deviation was formed.

[0154] [Example 10]

[0155] In the polymer extrusion process, the number of holes in the spinning tube 4 was set to 72, and polyamide 66 fibers with a length of 470 dtex and 72 filaments were produced. Otherwise, the process was carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 2 below. A slightly larger water droplet contact angle resulted in a slightly larger and slightly deviated EC / V coefficient.

[0156] [Example 11]

[0157] In the polymer extrusion process, polyamide 66 fibers with a length of 350 dtex and 136 filaments are produced. In the weaving process, the warp and weft yarn density is set to 60 yarns × 60 yarns per 2.54 cm, resulting in a woven fabric with a fabric coverage factor of 2245. Except for the extrusion and weaving processes described above, the process is carried out in the same manner as in Example 1. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 2 below. An appropriate water droplet contact angle is achieved, resulting in a woven fabric with a small coefficient of variation in the non-interlaced area, a small coefficient of variation in EC / V, and a small deviation.

[0158] [Example 12]

[0159] In the polymer extrusion process, the number of holes in the spinning tube head 4 was set to 216, and polyamide 66 fibers with a length of 350 dtex and 216 filaments were produced. Except for the extrusion process described above, the process was carried out in the same manner as in Example 11. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 2 below. The deviation in the water droplet contact angle increased, resulting in a woven fabric with a slightly larger and slightly deviated EC / V variation coefficient.

[0160] [Example 13]

[0161] In the polymer ejection process, the number of holes in the spinning tube head 4 is set to 216. In the oiling process, two oiling devices are located at different positions along the yarn path, with their oiling sections facing each other. A finishing agent is applied, and polyamide 66 fibers with a length of 350 dtex and 216 filaments are produced. Except for the ejection and oiling processes described above, the process is performed in the same manner as in Example 11. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 2 below. The water droplet contact angle is appropriately sized; although the single yarn is fine, the deviation of the water droplet contact angle is small, resulting in a woven fabric with a small coefficient of variation in the non-interlaced area, a small coefficient of variation in EC / V, and a small deviation.

[0162] [Example 14]

[0163] In the polymer ejection process, the number of holes in the spinning tube 4 was set to 216, producing polyamide 66 fibers with a length of 235 dtex and 216 filaments. In the weaving process, the warp and weft yarn density was set to 72 yarns × 72 yarns per 2.54 cm, resulting in a woven fabric with a fabric coverage factor of 2207. Except for the ejection and weaving processes described above, the process was performed in the same manner as in Example 1. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 2 below. The deviation in the water droplet contact angle increased, resulting in a woven fabric with a slightly larger and slightly deviated EC / V variation coefficient.

[0164] [Example 15]

[0165] In the polymer ejection process, the number of holes in the spinning tube head 4 is set to 216. In the oiling process, two oiling devices are located at different positions along the yarn path, with their oiling sections facing each other. The finishing agent is applied, and polyamide 66 fibers with a length of 235 dtex and 216 filaments are produced. Except for the oiling process described above, the process is carried out in the same manner as in Example 14. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabrics are shown in Table 2 below. The water droplet contact angle is appropriately sized, and although the single yarn is fine, the deviation of the water droplet contact angle is small, resulting in a woven fabric with a small coefficient of variation in the non-interlaced area, a small coefficient of variation in EC / V, and a small deviation.

[0166] [Comparative Example 1]

[0167] In the oiling process, the adhesion rate of the ionic surfactant was set to 70 ppm, and otherwise carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabrics are shown in Table 3 below. A large water droplet contact angle resulted in a woven fabric with a large coefficient of variation and large deviation in EC / V.

[0168] [Comparative Example 2]

[0169] In the oiling process, the adhesion rate of the ionic surfactant was set to 840 ppm, and otherwise carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabrics are shown in Table 3 below. A small water droplet contact angle resulted in a woven fabric with a large coefficient of variation in EC / V, exhibiting deviations.

[0170] [Comparative Example 3]

[0171] In the winding process, the short-cycle shaking amplitude ratio B was set to 0.2, and the package width W was set to 8.5 cm. Otherwise, the process was carried out in the same manner as in Example 1. The physical properties of the resulting polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 3 below. A woven fabric with a large coefficient of variation in the non-interlaced area, a large coefficient of variation in EC / V, and deviations was formed.

[0172] [Comparative Example 4]

[0173] In the winding process, the package width W was set to 32 cm, and otherwise performed in the same manner as in Example 1. The physical properties of the obtained polyamide 66 fibers and the evaluation results of the woven fabric are shown in Table 3 below. A woven fabric with a large coefficient of variation in the non-interlaced area, a large coefficient of variation in EC / V, and deviations was formed.

[0174] [Table 1]

[0175]

[0176] [Table 2]

[0177]

[0178] [Table 3]

[0179]

[0180] Industrial availability

[0181] The synthetic fiber for airbags of the present invention exhibits excellent water inclusion (instant hydrophilicity of the yarn) during weaving using WJL, thus significantly improving weft yarn flight (following of water jets), and possesses a uniform non-interlaced area, resulting in excellent uniform and straight flight characteristics (uniform yarn flight). Due to these two characteristics, there is no deviation in the quality along the width of the base fabric, enabling high-speed weaving. Therefore, the synthetic fiber for airbags of the present invention can be suitably used as yarn, particularly weft yarn, for weaving woven fabrics for airbags.

[0182] Explanation of reference numerals in the attached figures

[0183] 1. Packaging

[0184] 2 Paper tubes

[0185] 3. Spinneret

[0186] 4. Spinning tube head

[0187] 5. Cold air chamber

[0188] 6. Oil supply device (finishing agent dispensing device)

[0189] 7 Traction Rollers

[0190] 8 First Roller

[0191] 9 Second Roller

[0192] 10 Third Roller

[0193] 11 Fourth Roller

[0194] 12 Yarn Path Control Guide

[0195] 13 Interweaving device

[0196] 14 Winding Machine

[0197] 15 Single yarn

[0198] 16 Water Droplets

[0199] W is the width of the roll-up package.

[0200] B Short-period oscillation amplitude ratio

[0201] θ is the lead angle at the start of winding.

[0202] α Water droplet contact angle

[0203] a. Length of the non-interlaced portion

[0204] b. Width of the non-interlaced portion

Claims

1. A synthetic fiber for airbags, characterized in that, It is a multifilament synthetic fiber for airbags with interlaced and non-interlaced portions. The water droplet contact angle on the surface of the single yarn is 50~70°, and the deviation of the non-interlaced portion area per 20cm is more than 3% and less than 8% in terms of CV value. The deviation of the water droplet contact angle on the surface of the single yarn in the longitudinal direction is less than 5% in terms of CV value.

2. The synthetic fiber for airbags according to claim 1, wherein, The water droplet contact angle on the surface of the single yarn is 50~65°.

3. The synthetic fiber for airbags according to claim 1, wherein, The deviation of the non-interlaced area per 20cm is 3% or more and 7% or less in terms of CV value.

4. The synthetic fiber for airbags according to claim 1, wherein, The area of ​​the non-interlaced portion is evaluated as 12.5~20cm in every 20cm range along the yarn length direction. 2 The range.

5. The synthetic fiber for airbags according to claim 4, wherein, The area of ​​the non-interlaced portion is evaluated as 14~17.5 cm² per 20 cm along the yarn length. 2 The range.

6. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein the number of single yarns is 60 to 250.

7. The synthetic fiber for airbags according to claim 6, wherein the number of single yarns is 120 to 250.

8. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein the single yarn fineness is 1 to 7 dtex.

9. The synthetic fiber for airbags according to claim 8, wherein the single yarn fineness is 1~3 dtex.

10. The synthetic fiber for airbags according to claim 8, wherein the single yarn fineness is 1.0~1.8 dtex.

11. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein the number of single yarns is 200 to 250 and the single yarn fineness is 1.0 dtex to 1.8 dtex.

12. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein the interlacing degree is 10 to 35 strands / m.

13. The synthetic fiber for airbags according to claim 12, wherein the interlacing degree is 15-30 strands / m.

14. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein, The deviation of the water droplet contact angle on the surface of the single yarn in the length direction is greater than 1% and less than 4.5% in terms of CV value.

15. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein the finishing agent adhesion rate is 0.6 to 1.2 by weight.

16. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein, Anionic surfactants containing phosphorus atoms and / or anionic surfactants containing sulfur atoms adhere at 200-500 ppm relative to the fiber weight.

17. The synthetic fiber for airbags according to claim 16, wherein, The anionic surfactant containing phosphorus atoms and / or the anionic surfactant containing sulfur atoms are attached at 250-500 ppm relative to the fiber weight.

18. The synthetic fiber for airbags according to claim 16, wherein, The anionic surfactant containing phosphorus atoms and / or the anionic surfactant containing sulfur atoms are attached at 300-500 ppm relative to the fiber weight.

19. The synthetic fiber for airbags according to any one of claims 1 to 5, wherein it satisfies the following conditions (1) to (4): (1) Total fineness is 150~800 dtex; (2) Strength is 7.5~9 cN / dtex; (3) Elongation rate is 15-25%; and (4) The shrinkage rate of boiling water is 4~11%.

20. The rolled packaging body of synthetic fibers for airbags according to any one of claims 1 to 5, wherein, The width W of the packaging body is 8~22cm.

21. The rolled packaging body of synthetic fibers for airbags according to claim 20, wherein, The width W of the packaging body is 8~18cm.

22. The method for manufacturing synthetic fibers for airbags according to any one of claims 1 to 19, characterized in that, The following processes are included: The process of taking synthetic fibers spun by melt spinning into a tube using a take-up machine equipped with a traverse mechanism for rocking the yarn along the tube axis, via one or more finishing agent application devices, multiple stretching rollers, an interlacing application device, and one or more yarn path control guides provided before and after the interlacing application device. The tension before winding in this process is 0.1~0.3cN, and the short-cycle oscillation amplitude ratio B of the yarn oscillation based on the traverse mechanism is 0.5~5%.

23. The method for manufacturing synthetic fibers for airbags according to claim 22, wherein, The width W of the package obtained by winding synthetic fibers into a tube is 8~22cm.

24. The method for manufacturing synthetic fibers for airbags according to claim 22 or 23, wherein, Using the aforementioned finishing agent application device, the finishing agent is applied in such a way that 200 to 500 ppm of anionic surfactant containing phosphorus atoms and / or anionic surfactant containing sulfur atoms are applied relative to the fiber weight.

25. The method for manufacturing synthetic fibers for airbags according to claim 22 or 23, wherein, There are two or more finishing agent application devices at different positions in the yarn path direction, and the oil supply sections of at least two finishing agent application devices face each other.

26. A method for manufacturing a woven fabric for an airbag, comprising the following steps: In a water jet loom, the weft yarn is made of the synthetic fiber for airbags as described in any one of claims 1 to 5, and the fabric is woven at a weaving speed of 800 rpm or higher.

27. The method for manufacturing the woven fabric for airbags according to claim 26, wherein, The synthetic fiber used in the airbag has 200-250 yarns per strand, and the yarn fineness is 1.0 dtex to 1.8 dtex.

28. The method for manufacturing the woven fabric for airbags according to claim 26, wherein, The fabric coverage factor of woven fabrics is above 2000 and below 2500.

29. A method for manufacturing an airbag woven fabric according to any one of claims 26 to 28, wherein, The deviation of the slip resistance to stiffness ratio EC / V of woven fabrics, expressed as CV value, is less than 13.7%.

30. The method for manufacturing the woven fabric for an airbag according to claim 29, wherein, The deviation of the ratio of slip resistance to stiffness, EC / V, is greater than 8.4% in terms of CV value.

31. A method for manufacturing an airbag woven fabric according to any one of claims 26 to 28, wherein, The ratio of slip resistance to stiffness, EC / V, is above 52.9 N / N.

32. The method for manufacturing the woven fabric for airbags according to claim 31, wherein, The ratio of slip resistance to stiffness, EC / V, is below 60.1 N / N.

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