CN117098882A

CN117098882A - Synthetic fiber for airbag and method for producing woven fabric for airbag using same

Info

Publication number: CN117098882A
Application number: CN202280025344.0A
Authority: CN
Inventors: 桑原健斗
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp
Priority date: 2021-04-02
Filing date: 2022-04-01
Publication date: 2023-11-21
Also published as: JPWO2022211130A1; WO2022211130A1

Abstract

Provided is a synthetic fiber for an airbag, which can be suitably used for warp and weft yarns when weaving a woven fabric for use in an airbag by WJL. A synthetic fiber for an airbag, which is a multifilament synthetic fiber for an airbag having interlacing parts and non-interlacing parts, wherein the contact angle of water drops on the surface of a single yarn is 50-75 DEG, and the variation of the area of the non-interlacing parts per 20cm is 10% or less in CV value, a wound package of the synthetic fiber for an airbag, a method for producing the package, and a method for producing a woven fabric for an airbag using the synthetic fiber for an airbag as a weft yarn.

Description

Synthetic fiber for airbag and method for producing woven fabric for airbag using same

Technical Field

The present invention relates to a synthetic fiber for an airbag and a method for producing a woven fabric for an airbag using the same.

Background

The airbag device is mounted for the purpose of protecting a passenger in the event of a collision of an automobile. The airbag protects a passenger by inflating an airbag cushion by generating high-pressure gas by an inflator after sensing a collision of the automobile. In order to reliably protect the occupant, it is necessary to maintain the inflated state of the airbag cushion for a long period of time, in other words, internal pressure retention is required. In addition, in recent years, there have been far-end curtain airbags for preventing a driver from colliding with a passenger in a passenger seat and pedestrian airbags for protecting pedestrians, but these airbags are required to be stored in a narrow place of a seat or an engine cover, and further, the compactness of an airbag cushion has been sought.

The manufacturing process of the air bag cushion mainly comprises four processes of spinning, weaving, sewing and assembling. In the weaving process, a Water Jet Loom (WJL) is often used. WJL jets water obliquely from the side to the yarn entering from the rear of the nozzle, and the yarn is weft inserted by the water flow of the formed water column. The weft yarn inserted at the position where the warp yarn opens is controlled on the opposite side of the nozzle, and then beaten up to form a woven fabric.

In the weaving process using WJL, in recent years, the weaving speed has been increased to improve productivity, and the efficiency and labor of the process have been improved.

In patent document 1 below, the weft yarn is stably and reliably flown by restricting the diffusion of water ejected from the weft insertion nozzle, thereby improving the weaving efficiency. On the other hand, if the weaving speed is increased depending on the yarn, a lack of flight may occur during weft insertion, resulting in a weaving failure.

In order to solve this problem, patent document 2 below discloses a synthetic fiber for an airbag, which is obtained by performing interlacing such that the flyability of weft yarns during weaving is improved. This makes it possible to achieve high-speed weaving at 850rpm to 1000rpm, and to reduce the drawbacks in this step. However, it only mentions the number of weaving shutdowns and is not described with respect to the quality of the woven fabric article.

In addition, in patent document 3 below, the intermediate load elastic modulus of the synthetic fiber is increased, the intermediate elastic elongation is reduced, the responsiveness to high-speed weft insertion is improved, and the variation in the intermediate load elastic modulus is suppressed, whereby the woven fabric woven at a high speed of 900rpm also achieves uniform air permeability.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2000-34646

Patent document 2: japanese patent laid-open No. 2007-126796

Patent document 3: japanese patent No. 5253685

Disclosure of Invention

Problems to be solved by the invention

As described above, the conventional technique realizes weaving of a woven fabric that becomes uniform in air permeability even at high-speed weaving by improving responsiveness to force of weft yarn in the flight direction and suppressing variation in yarn length direction of responsiveness. The air permeability of the woven fabric is a parameter related to air leakage occurring from the surface of the woven fabric, and affects the internal pressure retention of the airbag. However, when the airbag is deployed, the air leakage occurring from the sewn portion is more serious than the air leakage occurring from the surface of the woven fabric, and the air permeability of the woven fabric has little influence on the internal pressure retention.

The parameter related to the air leakage occurring from the sewn portion of the woven fabric is the slip resistance. If the slip resistance is large, when the sewn portion is loaded with stress during airbag deployment, the sewn portion is less likely to undergo needle eye deflection and the internal pressure is less likely to decrease.

On the other hand, there is stiffness as a parameter related to the stowability of the airbag in the vehicle. The airbag cushion is folded and stored, and is mounted in a vehicle as an airbag device, and if the stiffness is high, the folded volume becomes large, and the airbag cushion cannot be fully stored.

In order to improve the slip resistance, a method of increasing the weaving density and the crimp ratio is generally adopted, but these have a problem of impairing the softness of woven fabrics. Accordingly, there is a strong demand for an airbag woven fabric having high slip resistance and high flexibility, and for an airbag raw yarn that can contribute to both properties.

Under the circumstances, the present invention has been made to solve the problems of providing synthetic fibers for an airbag that can be suitably used in warp and weft yarns when weaving a woven fabric used for an airbag with WJL. In particular, it is possible to provide a synthetic fiber for an airbag, which can reduce uneven tension when a weft yarn flies at a high speed and reaches the opposite side of a nozzle, has uniform following ability for water jet, and can suppress quality deviation in the width direction of a woven fabric when flying at a high speed (which is formed by stabilizing a polyamide yarn in the width direction of the woven fabric and then forming a structure after instantaneous elastic recovery thereof), and can achieve both high slip resistance and high flexibility in which the relationship between the slip resistance and the high flexibility is eliminated.

Solution for solving the problem

The inventors have unexpectedly found that: in the weaving of the woven fabric described above using WJL, uniformity of the non-woven portion area is important for uniform flying property of yarn, and instantaneous hydrophilicity of yarn is important for follow-up property with respect to jet water, thereby completing the present invention.

Namely, the present invention is as follows.

[1] A synthetic fiber for an airbag, characterized in that the synthetic fiber is a multifilament synthetic fiber for an airbag having interlacing parts and non-interlacing parts, the contact angle of water drops on the surface of a single yarn is 50-75 DEG, and the variation of the area of the non-interlacing parts per 20cm is 10% or less in CV value.

[2]According to the above [1]]The synthetic fiber for an airbag, wherein the non-interlaced part area is 12.5 to 20cm in the evaluation per 20cm range in the yarn length direction ² Is not limited in terms of the range of (a).

[3] The synthetic fiber for an air bag according to the above [1] or [2], wherein the number of single yarns is 60 to 250.

[4] The synthetic fiber for an airbag according to any one of the above [1] to [3], wherein the single yarn fineness is 1 to 7dtex.

[5] The synthetic fiber for an airbag according to any one of the above [1] to [4], wherein the number of single yarns is 200 to 250 and the fineness of the single yarns is 1.0dtex to 1.8dtex.

[6] The synthetic fiber for an airbag according to any one of the above [1] to [5], which has an interweaving degree of 10 to 35 pieces/m.

[7] The synthetic fiber for an air bag according to any one of the above [1] to [6], wherein the variation in the contact angle of water droplets on the surface of the single yarn in the longitudinal direction is 5% or less in terms of CV value.

[8] The synthetic fiber for an airbag according to any one of the above [1] to [7], wherein the finishing agent adhesion rate is 0.6 to 1.2% by weight.

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

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

(1) The total fineness is 150-800 dtex;

(2) The strength is 7.5-9 cN/dtex;

(3) The elongation is 15-25%; and

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

[11] The synthetic fiber roll package for an air bag according to any one of the above [1] to [10], wherein the width W of the package is 8 to 22cm.

[12] A method for producing a synthetic fiber for an airbag, comprising the steps of:

A step of winding synthetic fibers spun by melt spinning into a tube by using a winding machine equipped with a traverse mechanism for oscillating a sliver in the tube axis direction through 1 or more finishing agent applying (oil feeding) devices, a multistage drawing roll, a interlacing applying device, and 1 or more yarn path control guides provided before and after the interlacing applying device,

the tension before winding in this step is 0.1 to 0.3cN, and the short-period vibration amplitude ratio B during the vibration of the sliver by the traverse mechanism is 0.5 to 5%.

[13] The method for producing a synthetic fiber for an airbag according to the above [12], wherein the width W of the package obtained by winding the synthetic fiber into a tube is 8 to 22cm.

[14] The method for producing a synthetic fiber for an air bag according to the above [12] or [13], wherein the finishing agent is applied by the finishing agent applying means so that 200 to 500ppm of the anionic surfactant containing a phosphorus atom and/or the anionic surfactant containing a sulfur atom is adhered to the weight of the fiber.

[15] The method for producing a synthetic fiber for an air bag according to any one of the above [12] to [14], wherein the finishing agent applying device has 2 or more different positions in the yarn path direction, and the oil supply portions of at least 2 finishing agent applying devices face each other in the front direction.

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

in the water jet loom, the synthetic fiber for an air bag according to any one of the above [1] to [10], is used as a weft yarn, and a fabric is produced at a weaving speed of 800rpm or more.

ADVANTAGEOUS EFFECTS OF INVENTION

The synthetic fiber for an airbag of the present invention has a specific range of variation in the water drop contact angle and the non-woven portion area on the surface of a single yarn, and thus, in weaving using WJL, the weft yarn flying property (following property for jet water) is dramatically improved, and the uniform and straight-line flying property (uniform flying property of yarn) is excellent. Due to these two characteristics, high-speed weaving is possible without quality variation in the width direction of the base fabric.

Drawings

Fig. 1 is a view illustrating a width W of a wound package of synthetic fibers for an airbag.

Fig. 2 is a view illustrating an example of an apparatus for producing synthetic fibers for airbags.

Fig. 3 is a diagram illustrating the definition of the short-period shake width ratio B and the lead angle θ (lead angle) at the start of winding for determining the speed increase/decrease method of the winding machine.

Fig. 4 is an explanatory diagram in measurement of the contact angle of water droplets.

Fig. 5 is an explanatory diagram for defining the length a and the width b of the non-interleaved section for determining the non-interleaved section and the CV value thereof.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

An embodiment of the present invention is a synthetic fiber for an airbag, which is a multifilament synthetic fiber for an airbag having interlacing parts and non-interlacing parts, wherein a contact angle of water drops on a surface of a single yarn is 50 to 75 °, and a variation in area of the non-interlacing parts per 20cm is 10% or less in CV value.

The synthetic fiber for an airbag according to the present embodiment has a water drop contact angle of 50 ° or more and 75 ° or less on the surface of a single yarn. The water drop contact angle refers to: as shown in fig. 4, a certain amount of water droplets were attached to a single yarn of synthetic fiber for an airbag, and the contact angle was observed from the side over time, and the contact angle value was shown to be the maximum value within 100ms (8 ms for 1 frame of video).

If the contact angle of the water drop is 50 ° or more, the surface tension of the injected water at the time of weft insertion moderately acts in the sliver, and the yarn can fly without loosening. Since the yarn does not loosen, the air resistance of the sliver is reduced during flying, the flying property of the weft yarn is improved, and the weft insertion property is stabilized at a high speed. Since weft insertion behavior is stabilized, weft yarns are woven into warp yarns after instantaneous elastic recovery is stabilized, and thus, the uniformity of the physical properties of the woven fabric of the airbag in high-speed weaving is facilitated. In addition, since the water jet contained in the sliver becomes uniform, uniform flight is exhibited, contributing to uniformity of the physical properties of the woven fabric. In addition, if the contact angle is 75 ° or less, the hydrophilicity of the sliver becomes high, and the following property to the injected water is improved, so that the following problem does not occur: the phenomenon of a tumor (explosion phenomenon of the sprayed water) occurs, the sprayed water flies, and the sliver does not reach the opposite side of the nozzle, so that insufficient flying is caused, and weaving faults are generated. Since the inclusion of the sprayed water in the sliver is rapidly generated in the millisecond unit by making the contact angle of the water drop low, the spreading of the non-woven portion is rapidly generated, and the flying property by the sprayed water becomes efficient, thereby contributing to the uniformity of the physical properties of the woven fabric for the same reason as described above. The lower the water drop contact angle α is, the more uniform the properties of the airbag base fabric are. The water drop contact angle is more preferably 50 to 70 °, and still more preferably 50 to 65 °.

The deviation in the yarn length direction of the water drop contact angle on the single yarn surface of the synthetic fiber for an airbag in this embodiment is 5% or less in terms of CV value (coefficient of variation). If the CV value is 5% or less, the adhesion of the finishing agent to the single yarn is uniform in the yarn length direction, the amount of water contained in the sliver at the time of weft insertion becomes uniform, and when the deviation in flying property is small, the deviation in the ratio of slip resistance to stiffness (EC/V) can be reduced, in other words, a woven fabric of uniform quality, in particular, a woven fabric of uniform quality in the width direction of the base fabric can be obtained. The CV value is preferably 4.5% or less. The lower limit of the CV value is not particularly limited, and may be 1% or more as an economically realizable range.

The variation in the area of the non-woven portion per 20cm of the synthetic fiber for an airbag in the present embodiment is 10% or less calculated as the CV value (coefficient of variation). If the CV value is 10% or less, the length a of the non-woven portion and the sliver expansion width b due to the surface tension of the finishing agent as shown in fig. 5 are uniform, the amount of water contained in the sliver becomes uniform at the time of weft insertion at the time of weaving by WJL, and the variation in flying property disappears, so that the variation in the ratio of slip resistance to stiffness (EC/V) can be reduced, in other words, a woven fabric of uniform quality, in particular, a woven fabric of uniform quality in the width direction of the base fabric can be obtained. 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 may be 3% or more as an economically realizable range. In the measurement of the 20cm yarn length, if the non-interlaced portion is uniform wherever it is taken, the flying property based on the injected water becomes uniform.

The area of the non-interlaced portion of the synthetic fiber for an airbag in the present embodiment is preferably 12.5 to 20cm in the evaluation per 20cm range in the yarn length direction ² . If the non-interlaced part area is 12.5cm ² As described above, the sliver fully contains water, and the weft yarn has good flying properties, and the loom can be prevented from being stopped. On the other hand, if the area of the non-woven portion is 20cm ² In the following, the length of the interweaving portion can be appropriately set, and the yarn is not loosened, thereby preventing the loom from being stopped. The area of the non-woven portion is more preferably 14 to 17.5cm in the evaluation per 20cm range in the yarn length direction ² 。

In the synthetic fiber for an airbag of the present embodiment, the anionic surfactant containing a phosphorus atom and/or the anionic surfactant containing a sulfur atom is preferably attached to the fiber in an amount of 200 to 500ppm based on the weight of the fiber. By containing 200ppm or more of the ionic surfactant, the contact angle of the water drop becomes sufficiently low, the yarn becomes further hydrophilic, and the follow-up property against the jet water is improved and the weft yarn flying property is improved at the time of weft insertion in the weaving process. On the other hand, if the adhesion rate is 500ppm or less, the water drop contact angle is too small, and the yarn is not loosened when the weft yarn is flown during weaving. The adhesion rate of the anionic surfactant to the weight of the fiber is more preferably 250 to 500ppm, still more preferably 300 to 500ppm. The anionic surfactant containing a phosphorus atom is not particularly limited, and examples thereof include metal salts or amine salts of alkyl phosphates (hereinafter abbreviated as phosphate esters) and metal salts or amine salts of polyoxyethylene alkyl phosphate esters. More specifically, for example, potassium lauryl phosphate, sodium lauryl phosphate, potassium octyl phosphate, sodium octyl phosphate and the like are exemplified. The anionic surfactant containing a sulfur atom is not particularly limited, and examples thereof include alkane sulfonates. The method of attaching the ionic surfactant is not particularly limited, and it is preferable to attach the ionic surfactant by mixing the ionic surfactant with a finishing agent.

The interweaving degree of the synthetic fibers for an airbag in the present embodiment is preferably 10 to 35 pieces/m in the measurement by the water immersion method as shown in fig. 5. If the degree of interlacing is 10 pieces/m or more, the bundling property required for warp yarns at the time of weaving is sufficiently satisfied, and the reduction of the weaving efficiency or the quality of woven fabric is not impaired. On the other hand, if the number of interweaving is 35/m or less, the non-interweaving area becomes proper, the flying performance of the weft yarn becomes good, and the variation in the length of the single yarn in the sliver longitudinal direction is small, so that the occurrence of yarn breakage and burrs during weaving can be suppressed, and the stop of the loom can be prevented. The degree of interleaving is more preferably 15 to 30 pieces/m.

The synthetic fiber for an airbag of the present embodiment is multifilament, and the number of single yarns is preferably 60 to 250. If the number of single yarns is 60 or more, the number of single yarns required for forming the interlacing is sufficient, and the interlacing cannot be formed or loosened. 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 air energy utilization efficiency for imparting interlacing is good, and uniform and good interlacing can be made. The number of single yarns is more preferably 200 or less.

The multifilament synthetic fiber for an airbag according to the present embodiment preferably has a single yarn fineness of 1 to 7dtex. If the single yarn fineness is 1dtex or more, the tensile characteristics such as the single yarn toughness are sufficient, and the occurrence of fuzzing in the yarn making step can be suppressed. On the other hand, if the single yarn fineness is 7dtex or less, the sliver can be rotated at the time of the interlacing process with a smaller energy, and a desired interlacing state can be obtained. Further, if the yarn length is 4dtex or less, the space between the individual yarns becomes small, and therefore, the effect of the surface tension of the water jet in the sliver at the time of weft insertion becomes large, and the yarn can fly further without loosening. The single yarn fineness is more preferably 2 to 7dtex from the viewpoint of obtaining sufficient stretch properties, and is more preferably 1 to 4dtex, further preferably 1 to 3dtex, further preferably 1.0dtex or more and 1.8dtex or less from the viewpoint of flying property at the time of weft insertion.

The multifilament synthetic fiber for an airbag according to the present embodiment preferably has a number of single yarns of 200 to 250 and a fineness of 1.0dtex or more and 1.8dtex or less. If the single yarn fineness is 1.0dtex or more and 1.8dtex or less, the woven fabric is further flexible. If the number of single yarns is 200 to 250, the multifilament has sufficient mechanical properties as a multifilament fiber even if the fineness of the single yarns is low of 1.0dtex or more and 1.8dtex or less.

The multifilament synthetic fiber for an airbag according to the present embodiment desirably has physical properties of 150 to 800dtex total fineness, 7.5 to 9cN/dtex strength, 15 to 25% elongation and 4 to 11% boiling water shrinkage.

If the total fineness is 150dtex or more, the woven fabric for an airbag has sufficient mechanical properties when produced. On the other hand, if the total fineness is 800dtex or less, bundling property is easily imparted in the interleaving imparting step. In other words, if the fineness is increased, it is necessary to significantly increase the air pressure and air flow rate required for yarn rotation for proper interlacing, and not only the cost of the increment of the auxiliary material increases, but also the yarn in the interlacing nozzle portion is easily damaged and burrs are easily generated, which results in a decrease in the grade of the yarn, and if the total fineness is 800dtex or less, this will not occur. The total fineness is more preferably 200 to 550dtex.

The (tensile) strength is preferably 7.5 to 9.0cN/dtex. If the tensile strength is as high as 7.5cN/dtex or more, it contributes to improvement of mechanical properties of the woven fabric. The tensile strength is more preferably 8.0cN/dtex or more. In consideration of other characteristics, manufacturing cost, and the like, the synthetic fiber for an airbag has a tensile strength of substantially 9.0cN/dtex or less.

The elongation is preferably 15 to 25%. If the elongation is 15% or more, there is no case where stress is excessively applied to the boundary portion between the expansion portion and the non-expansion portion at the time of expansion, and the expansion portion is broken. The elongation and strength are the same, and the elongation is preferably 25% or less in order to be balanced with the strength.

The boiling water shrinkage is preferably in the range of 4 to 11%. If the boiling water shrinkage is 4% or more, the woven fabric can be shrunk in the post-weaving process, which contributes to achieving a high density in the finishing of the woven fabric. The boiling water shrinkage is more preferably 6% or more. If the boiling water shrinkage is 6% or more, the woven fabric can be shrunk in the processing step after weaving, which contributes to uniformity of variation in mechanical properties of the woven fabric. The boiling water shrinkage is particularly preferably 7% or more. If the boiling water shrinkage is 11% or less, the warp and weft unbalance due to excessive shrinkage does not occur and the mesh is not induced when the woven fabric is produced. The boiling water shrinkage is more preferably 9.5% or less, and still more preferably 9% or less.

Another embodiment of the present invention is the synthetic fiber roll-up package for an airbag, wherein the width W of the package is 8 to 22cm.

As shown in fig. 1, the width W of the wound package (fiber package form of an object obtained by winding a fiber around a paper tube or the like by a winding machine) is preferably 8 to 22cm. If W is 8cm or more, the shape is stable and the transportation efficiency is also good. On the other hand, if the width W is 22cm or less, the variation in the area of the non-woven portion is reduced due to the difference in tension between the center and the ends in the width direction of the package at the time of winding. W is more preferably 8 to 18cm.

The synthetic fibers constituting the synthetic fibers for an airbag according to the present embodiment are preferably long fibers made of multifilament yarns of polyamide and polyester. Polyamide fibers are particularly preferred, and have high heat resistance because of their high melting point and large heat capacity. For example, 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 can be cited. Among them, polyamide 6/6 fibers mainly formed of polyhexamethylene adipamide fibers are preferable. Polyhexamethylene adipamide refers to polyamide fibers composed of 100% of hexamethylenediamine and adipic acid and having a melting point of 250 ℃ or higher. The polyamide 6/6 fiber of the present invention may be a fiber formed from a polymer obtained by copolymerizing or blending polyhexamethylene adipamide with polyamide 8, polyamide 6.I, polyamide 10, polyamide 6/T, etc. in a range of not lower than 250 ℃.

Another embodiment of the present invention is a method for producing a synthetic fiber for an airbag, comprising the steps of:

a step of winding synthetic fibers spun by melt spinning into a tube by using a winding machine having a traverse mechanism for oscillating a sliver in a tube axis direction through 1 or more finishing agent applying (oil feeding) devices, a multi-stage drawing roller, a interlacing applying device, and 1 or more yarn path control guides provided before and after the interlacing applying device,

Hereinafter, a method for manufacturing a wound package of synthetic fiber for an airbag according to the present embodiment will be described.

Fig. 2 is an explanatory view showing an example of an apparatus for producing synthetic fibers for airbags according to the present embodiment. First, the polymer in a molten state is homogenized by a part of a spinning machine called a spinneret 3, and is spun from a spinneret 4. The spun polymer is solidified by cold air from the cooling chamber 5 to form strands. Thereafter, after finishing agent is applied to the sliver wound around each end by the oil feeder 6, the sliver advances to a drawing step based on a roller group consisting of the pull roller 7 and the first to fourth rollers 8 to 11. That is, after the sliver is drawn at a predetermined speed by the roller 7, the sliver is introduced into the first stage roller 8 with a small tension, and is stretched by the heated stretching rollers 9, 10, and 11 of plural stages from the first stage roller 8. Thereafter, the yarn is supplied to the weaving machine 13 through the yarn path control guide 12, and is wound by the winding machine 14 through the yarn path control guide 12.

The oil supply device 6 is generally of a roll type or a nozzle type. The oil supply device 6 may be configured so as to have 1 or more, preferably 2 or more at different positions in the yarn path direction, and at least two of the oil supply portions face each other in the front direction. In particular, when the single yarn fineness is 1,0 to 1.8dtex, the following tends to occur: the shaking of the yarn in the solidification step by the cold air from the cooling chamber 5 is transmitted to the oil supply step, and the yarn is disturbed in contact with the oil supply device 6, so that the adhesion of the finishing agent becomes uneven. By providing the oil feeder with 2 or more different positions in the yarn path direction and by making at least two of the oil feeder face-sides in the direction, contact disturbance of the yarn to the oil feeder can be suppressed, and therefore even if the single yarn fineness is 1.0 to 1.8dtex, the finishing agent can be uniformly attached, and deviation in the yarn length direction of the water drop contact angle on the surface of the single yarn can be suppressed.

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 wt%. A sliver having a finish adhesion rate of 1.2 wt% or less hardly causes the weft yarn to fly due to tackiness (tackiness). If the finishing agent adhesion rate is 0.6 wt% or more, the occurrence of single yarn burrs during stretching in the yarn making process can be suppressed.

From the viewpoint of sliver quality and industrial material use, among the components of the finishing agent to be applied to the synthetic fibers by the oil supply device 6, in addition to the ionic surfactant, it is preferable to use a component having excellent smoothness and heat resistance for smooth drawing of the sliver in the sliver making process.

The smoothing agent is preferably an ester compound. It is preferable to contain at least one ester compound selected from ester compounds having 3 or more ester bonds in the molecule and ester compounds having a sulfur element in the molecule.

Examples of the ester compound having a sulfur element in the molecule include (1) ester compounds of a dicarboxylic acid such as dialkyl thiodipropionate and a monohydric alcohol, and (2) ester compounds of a monocarboxylic acid such as alkyl mercaptopropionate and a monohydric alcohol.

Examples of the ester compound having 3 or more ester bonds in the molecule include (3) ester compounds of a monohydric carboxylic acid and a polyhydric alcohol such as trimethylolpropane trionearer, glycerol fatty acid ester, pentaerythritol tetra fatty acid ester, and trimethylolpropane fatty acid ester; (4) Ester compounds of polycarboxylic acids and monohydric alcohols such as trialkyl trimellitates and triethyl citrate; (5) Natural oils such as castor oil, palm oil, and refined rapeseed oil. These components may be used singly or in combination of 1 or more than 2.

Nonionic surfactants can be used as emulsifying, friction modifiers.

Examples thereof include (1) polyoxyalkylene polyol fatty acid ester type nonionic surfactants such as ether ester compounds obtained by condensing at least 1 compound selected from polyethylene glycol dialkylate, polyoxyethylene sorbitan monoalkylate, polyoxybutylene sorbitan trialkylate, polyoxypropylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene propylene hydrogenated castor oil trialkylate, polyoxyethylene hydrogenated castor oil trialkylate, ethylene oxide (hereinafter referred to as EO) adduct of castor oil and EO adduct of hydrogenated castor oil with a monocarboxylic acid and a dicarboxylic acid; (2) More specifically, the nonionic surfactant is an ether type nonionic surfactant such as a polyoxyethylene fatty acid ester, a polyoxyethylene fatty acid ester methyl ether, a polyoxyethylene alkyl ether, a polyoxyethylene polyoxypropylene nonylphenyl ether, a polyoxyethylene alkylamino ether, a polyoxyethylene fatty acid amide ether, or the like; (3) A polyhydric alcohol partial ester type nonionic surfactant such as sorbitan fatty acid ester, and glycerin fatty acid ester; (4) And alkylamide nonionic surfactants such as diethanolamine fatty acid amide. These components may be used singly or in combination of 1 or more than 2.

The finishing agent may be diluted with mineral oil or the like, or may be prepared into an aqueous emulsion. Although not particularly limited, it is preferable to use the emulsion in view of compatibility with water in a subsequent step.

Yarn path control guides 12 for stabilizing the yarn travel are provided at the upstream and downstream portions of the interlacing device 13. The yarn running angle defined by these and the interlacing nozzle portion of the interlacing device is preferably maintained in the range of 1 to 10 ° to obtain synthetic fibers for airbags with little deviation. Setting the interval of the two yarn path control guides 12 to 50 to 90mm is preferable for obtaining a suitable non-interlacing area. The interlacing device 13 may use a known device for jetting a compressed fluid to the sliver by using an interlacing nozzle, and the compressed fluid jetted to the sliver is preferably supplied at an energy of 0.5 to 3.5 kW. The supply energy of the compressed fluid can be based on the supply pressure (Mpa) and the usage flow (Nm) ³ And/hr), and the supply pressure and the fluid introduction diameter of the interlacing nozzle are arbitrarily selected, thereby satisfying the supply energy range. Further, it is preferable to adjust the speed ratio between the fourth roller 11 and the coiler, and adjust the temperature of the fourth roller 11 within the above range, so that the coiling tension (pre-coiling tension) between the fourth roller 11 and the coiler 14 is in the range of 0.1 to 0.3 cN/dtex. If the winding tension is 0.1cN or more, the yarn will not fall off, and the shape of the package is stable. In addition, the density of the package is increased, and the transportation efficiency is improved. On the other hand, if the tension before winding is 0.3cN or less, the interlacing is sufficiently performed, the stable variation in the interlacing portion becomes small, and the tension fluctuation at the time of disassembling the package can be minimized, so that the package is excellent in the unwinding property.

The synthetic fiber for an airbag of the present embodiment is wound around a paper tube or the like by the winding machine 14. At this time, the sliver swings in the axial direction of the paper tube by the traverse mechanism, swings left and right between the widths of the winding package, and is packaged in a cylindrical shape. When the angle between the winding direction of the wound fiber sliver on the drum and the surface perpendicular to the rotation axis of the package drum is set to be the guide angle θ, (winding speed) = (winding speed) × (tan θ), the winding speed is controlled by setting the guide angle. In controlling the winding speed, it is preferable to apply a short-period shaking means in which the short-period shaking amplitude ratio B satisfies 0.5 to 5% in addition to the setting of the lead angle at a speed of swinging left and right between winding widths.

The short period shake amplitude ratio B is defined by fig. 3. B may be set on the traverse mechanism control application. The lead angle θ generally changes with the winding time, and by setting B, a fine change in lead angle can be applied to the lead angle at a certain winding time. For example, when the lead angle at the start of winding is 10 °, setting B to 1% can periodically apply a lead angle change of-0.1 to 0.1 ° (10±1%) to the lead angle that changes with time. In this case, the short period means a period of 0.1 to 2 seconds. B is set to prevent a spiral roll, the inventors found that: by performing such a variable interlacing, the winding tension of the yarn due to the interlacing can be suppressed, the interlacing is not impaired, and a uniform synthetic fiber for an airbag with small variation in the area of the non-interlacing portion can be obtained. If the short-period rocking width ratio B is set to 0.5% or more, the spiral coil can be avoided, and the tension fluctuation in winding can be suppressed. On the other hand, if B is set to 5% or less, there is no case where the yarn is dropped due to the deviation of the winding diameter caused by the guide angle in the short period.

Another embodiment of the present invention is a method for producing a woven fabric for an airbag, including the steps of:

in the water jet loom, the weft yarn is woven with the synthetic fiber for an air bag at a weaving speed of 800rpm or more.

In order to obtain synthetic fibers for airbags having good flyability in WJL, the improvement of the interlacing uniformity by adjusting the interlacing conditions and the improvement of the hydrophilicity of yarns by selecting a finishing agent are critical.

The synthetic fiber for an airbag according to the present embodiment is suitable for use as a weft yarn in weaving by WJL, particularly in high-speed weaving at 800rpm or more and weaving by a wide-width loom at 2m or more. The synthetic fiber for an airbag of the present embodiment can be suitably used even as a warp yarn used for weaving. The warp yarn before weaving may be subjected to a sizing treatment for improving smoothness. The oil may be removed by a scouring step after weaving, or the scouring step may be omitted. The woven fabric may be subjected to warm water or hot air treatment to shrink the woven fabric. The shrinkage step can be used to control the tension in the width direction of the woven fabric and the length direction of the fabric roll or to adjust the dimensional change rate.

The synthetic fiber for an airbag according to the present embodiment is suitably used for weaving a woven yarn to produce a high-density woven fabric, and preferably a woven fabric having a cloth cover factor of 2000 to 2500. If the cover modulus is 2000 or more, sufficient strength and low air permeability as woven fabrics for airbags can be ensured. On the other hand, if the cloth cover factor is 2500 or less, sufficient flexibility, thinness, and lightweight properties can be maintained. The cloth cover coverage coefficient is more preferably 2200 to 2500. In addition, the cover factor was { warp density (root/2.54 cm) × (warp denier (dtex)) ^1/2 Density of weft yarn (root/2.54 cm) × (weft yarn titer (dtex)) ^1/2 }。

The woven fabric for an airbag obtained by using the synthetic fiber of the present embodiment preferably has a slip resistance to stiffness ratio (EC/V) of 25N/N or more. If the EC/V is 25N/N or more, a woven fabric having low air permeability and flexibility sufficient for use as an airbag is formed. The EC/V is more preferably 35N/N or more, still more preferably 45N/N or more.

The woven fabric for an airbag obtained using the synthetic fiber for an airbag of the present embodiment preferably has a variation in the ratio of slip resistance to stiffness (EC/V) of 20% or less in terms of CV value. When the CV value of EC/V is 20% or less, an airbag woven fabric is formed which has little variation in the woven fabric width direction, stable base fabric properties, high slip resistance and good softness. Therefore, even if the airbag component is cut from any part of the woven fabric, the airbag has equivalent physical properties, and the reliability of the airbag is improved. The CV value of EC/V is more preferably 17.5% or less, and still more preferably 15% or less.

Examples

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the description, the compositions, physical properties, and measurement methods of the finishing agents used in the following examples and the like are as follows.

(1) Preparation of finishing agent

The finishing agent used in the spin finish was formulated by the following method.

First, a composition a as a base was prepared. The composition of composition A is as follows.

Dialkyl thiodipropionate (C12-18) esters: 40 parts by weight

Ethylene oxide 25 molar adduct of hydrogenated castor oil: 30 parts by weight

Propylene oxide/ethylene oxide alkyl (C12-18) polyethers: 30 parts by weight

An alkyl (C12-16) amine phosphate salt as an ionic surfactant was added to the above-described basic composition a so as to be "the content of the ionic surfactant in the finishing agent (wt%) as shown in tables 1 and 2 below, to prepare a finishing agent. Water was added so that the content of the finishing agent became 22 wt%, and an emulsion was prepared.

(2) Contact angle of water drop (°)

The contact angle of the water drop was measured by an automatic minimum contact angle meter (MCA-J, co., ltd.). Fig. 4 is an explanatory diagram of measurement of the contact angle of water droplets. As measurement conditions, a single yarn was fixed between measurement jigs in an indoor atmosphere having a temperature of 25 ℃ and a humidity of 50%, water at 24 ℃ was carried on 20pL single yarn, and a video image of the water drop was taken from the side by a camera, and the contact angle α was measured. The contact angle α was decreased with time (water was gradually infiltrated into the yarn), and the maximum value of the contact angle within 100ms (8 ms for 1 frame of video) was used as a measurement value in order to confirm instantaneous water fusion of the yarn. This operation was repeated with other single yarns, and the average value of the total 5 times was set as the water drop contact angle of each single yarn with respect to water.

(3) Coefficient of variation CV in the yarn length direction of the contact angle of a water drop

For the water drop contact angle, 10 points were measured for 1 single yarn per 5cm, and the CV value of the single yarn was obtained by the following calculation.

CV(％)＝(s/X)×100

Here, s is the standard deviation and X is the average value.

This operation was repeated with another 5 single yarns, and the average value of CV values of the individual yarns was used as the coefficient of variation CV in the yarn length direction of the water drop contact angle. The higher the CV value, the greater the deviation.

(4) Degree of interweaving (number/m)

The water bath for measuring the degree of interlacing had white lines at a portion 10cm apart from both ends, in other words, at a distance of 1m, each having a length of 1.2m, a width of 20cm, and a height (water depth) of 15cm, and water supplied from the supply port was discharged from the bath by overflowing. That is, the fresh water was supplied at a flow rate of about 500 cc/min to renew the water in the measurement bath. In the measurement method, both ends of the sliver cut to the extent of 1.2m were held, immersed in a measurement bath in a state of being applied with a tension of about 10cN, and visually read the number of interlaces (number/m) between the white threads when the water surface assumes a relaxed state. These measurements were repeated 50 times to evaluate the average value.

(5) Area of non-interlaced portion (cm) ² )

The sliver was immersed in the measurement bath in the same manner as in (4) above, and the length a of the non-woven portion and the width b of the non-woven portion of the sliver extending on the water surface were measured by a scale as shown in fig. 5, and a×b was defined as the non-woven portion area. The non-woven portion areas extending on the water surface were summed up in the area of 20cm in yarn length to obtain 1 measurement, and the measurement was repeated 25 times for each 20cm area to obtain an average value.

(6) Coefficient of variation CV of non-interlaced part area

The non-interleaved section area measured in (5) above was obtained by the following calculation. The higher the CV value, the greater the deviation.

CV(％)＝(s/X)×100

Here, s is the standard deviation and X is the average value.

(7) Denier of denier

The measurement was performed in accordance with JIS L1017.83a. The sample was taken out of the wound package by 50m using a length measuring machine having a frame circumference of 1.25 m.

(8) Strength (cN/dtex), elongation (%)

After the sample was left in a standard state (20 ℃ C., 65%) for 12 hours, the measurement was carried out in accordance with JIS L1017.5 a. The measurement was performed under conditions of a sample length of 250mm and a tensile speed of 300 mm/min.

(9) Shrinkage in boiling water (%)

The measurement was carried out in accordance with JIS L1017.14. Further, after immersing in boiling water, the solution was left in a room in a standard state (20 ℃ C., 65%) for 12 hours.

(10) Attachment rate of finishing agent (wt%)

The measurement was carried out in accordance with JIS L1017.16 b. Cyclohexane was used as the extraction solvent.

(11) Attachment rate (ppm) of ionic surfactant

Calculated from the value (the finish adhesion rate (wt%) measured in the above (10) and the concentration of the ionic surfactant in the finish (the ionic surfactant content (%)) in the finish.

(12) Weft slipping resistance EC (N)

The sample was subjected to a procedure of taking 5 times in the longitudinal direction of the base fabric and 5 times in the width direction of the base fabric, in other words, 25 samples were taken in total, and the weft slip resistance (N) was measured according to ASTM D6479 to calculate the average value thereof.

(13) Stiffness V (N) of base cloth

In the weft slipping resistance EC test of (12), samples were collected from adjacent portions of the samples, and the base fabric stiffness (N) of the obtained 25 samples was measured according to ASTM D4032, and the average value thereof was calculated.

Example 1

With the apparatus shown in fig. 2, a nylon 66 polymer having a 90% formic acid relative viscosity of 80 obtained by a polymerization method as a conventional method was melted at 300 ℃, and then homogenized by a spinneret 3, ejected by a spinneret 4 having a hole number of 136, and wound by a direct spinning drawing process to obtain a polyamide 66 fiber having 470dtex and 136 filaments. That is, the ejected nylon 66 polymer is cooled and solidified by the cool air chamber 5 to form a sliver, and then sequentially passes through the oil feeder 6, the pull roller 7, the first roller 8 to the fourth roller 11, and after stabilizing the yarn running by the yarn path control guide 12, the yarn is interlaced by the interlacing device 13, and is wound by the yarn path control guide 12 by the winding machine 14.

In the oil supplying step, the finishing agent was applied with a composition such that the adhesion rate was 0.7% and the adhesion rate of the ionic surfactant was 350ppm by using one finishing agent applying device. The compressed air supplied to the interlacing device 13 was set to 0.5MPa, and the air supply energy was set to 1.2kW. The distance between the yarn path control guides 12 was set to 7.3cm. The winding tension was adjusted to be 0.19 cN/dtex. Regarding the winding conditions, the short-period rocking width ratio B was set to 4.0%, the winding start lead angle was set to 7.8 °, and the package width W was set to 16cm. Physical properties of the obtained polyamide 66 fiber are shown in table 1 below.

The resulting polyamide 66 fiber was plain-woven using WJL at 900rpm to obtain a woven fabric. The obtained woven fabric was subjected to continuous scouring at 80℃and heat-set under conditions of overfeed of 4% and width shrinkage of 1% by the woven fabric fed by a tenter at 170℃to give a woven fabric having a weave density of 53 warp yarns and weft yarns per 2.54cm of 53X 53. The cloth cover coverage coefficient is 2298. The woven fabric was evaluated for slip resistance and base fabric stiffness. The evaluation results are shown in table 1 below. The contact angle of the water drop is proper, and the woven fabric with small variation coefficient of non-interweaving part area, small variation coefficient of EC/V and small deviation is formed.

Example 2

The procedure of example 1 was repeated except that the adhesion rate of the ionic surfactant in the oil supplying step was 490 ppm. Table 1 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The contact angle of the water drop is proper, and the woven fabric with small variation coefficient and small deviation of EC/V is formed.

Example 3

The procedure of example 1 was repeated except that the adhesion rate of the ionic surfactant in the oil supplying step was changed to 210 ppm. Table 1 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The contact angle of the water drop is proper but slightly larger, so that a woven fabric with slightly larger variation coefficient of EC/V and slightly deviation is formed.

Example 4

The procedure of example 1 was repeated except that the adhesion rate of the ionic surfactant was 490ppm in the oil supplying step and the width W of the package was 8.5cm in the winding step. Table 1 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The contact angle of the water drop is proper, and the woven fabric with small variation coefficient of non-interweaving part area, small variation coefficient of EC/V and small deviation is formed.

Example 5

The winding step was performed in the same manner as in example 1, except that the short-period vibration width ratio B was 1.5% and the package width W was 8.5 cm. Table 1 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. A woven fabric having a small variation coefficient of the non-woven portion area, a small variation coefficient of EC/V, and a small deviation is formed.

Example 6

The winding step was performed in the same manner as in example 1, except that the short-period vibration width ratio B was set to 0.8% and the package width W was set to 8.5 cm. Table 1 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. A woven fabric having a slightly larger variation coefficient of the non-woven portion area and a slightly larger variation coefficient of EC/V and having a slight deviation is formed.

Example 7

The winding process was performed in the same manner as in example 1, except that the width W of the package was 19.0 cm. Table 1 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. A woven fabric having a slightly larger variation coefficient of the non-woven portion area and a slightly larger variation coefficient of EC/V and having a slight deviation is formed.

Example 8

The same procedure as in example 1 was carried out except that the distance between the yarn path control guides 12 in the interlacing step was set to 7.8 cm. Table 1 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. A woven fabric having a large non-woven portion area, a small variation coefficient of EC/V, and a small deviation is formed.

Example 9

The same procedure as in example 1 was carried out except that the energy of air supply in the interlacing application step was set to 0.7 kW. Table 2 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. A woven fabric having a large non-woven portion area, a small variation coefficient of EC/V, and a small deviation is formed.

Example 10

The same procedure as in example 1 was carried out except that the number of holes of the spinneret 4 was 72 in the polymer ejection step to produce a polyamide 66 fiber having 470dtex and 72 filaments. Table 2 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The contact angle of the water drop is slightly larger, and a woven fabric with slightly larger variation coefficient of EC/V and slightly deviation is formed.

Example 11

In the polymer blowing step, a polyamide 66 fiber of 350dtex and 136 filaments was produced. In the weaving step, the weaving density of the warp yarn and the weft yarn was set to 60×60 yarns per 2.54cm, and a woven fabric having a cover factor of 2245 was obtained. The same procedure as in example 1 was carried out except for the above-mentioned ejection step and weaving step. Table 2 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The contact angle of the water drop is proper, and the woven fabric with small variation coefficient of non-interweaving part area, small variation coefficient of EC/V and small deviation is formed.

Example 12

In the polymer ejection step, the number of holes of the spinneret 4 was 216, and a polyamide 66 fiber having 350dtex and 216 filaments was produced. The same procedure as in example 11 was carried out except for the above ejection step. Table 2 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The deviation of the contact angle of the water drop becomes larger, and a woven fabric with slightly larger and slightly deviated variation coefficient of EC/V is formed.

Example 13

In the polymer blowing step, the number of holes of the spinneret 4 was 216, and in the oiling step, 2 oiling devices were provided at different positions in the yarn path direction, and the front sides of the oiling portions were made to face each other, and a finishing agent was applied to produce a polyamide 66 fiber having 350dtex and 216 filaments. The same procedure as in example 11 was carried out except for the above-described ejection step and oil supply step. Table 2 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The water drop contact angle is of a proper degree, and the deviation of the water drop contact angle is small in spite of the fineness of the single yarn, so that the woven fabric with small fluctuation coefficient of the non-interlaced part area, small fluctuation coefficient of EC/V and small deviation is formed.

Example 14

In the polymer ejection step, the number of holes of the spinneret 4 was 216, and a polyamide 66 fiber having 235dtex and 216 filaments was produced. In the weaving step, the weaving density of the warp yarn and the weft yarn was set to 72×72 yarns per 2.54cm, and a woven fabric having a cloth cover factor of 2207 was obtained. The same procedure as in example 1 was carried out except for the above-mentioned ejection step and weaving step. Table 2 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The deviation of the contact angle of the water drop becomes larger, and a woven fabric with slightly larger and slightly deviated variation coefficient of EC/V is formed.

Example 15

In the polymer blowing step, the number of holes of the spinneret 4 was 216, and in the oiling step, 2 oiling devices were provided at different positions in the yarn path direction, and the front sides of the oiling portions were made to face each other, and a finishing agent was applied to produce a polyamide 66 fiber having 235dtex and 216 filaments. The procedure of example 14 was repeated except for the above-mentioned oil supplying step. Table 2 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The water drop contact angle is of a proper degree, and the deviation of the water drop contact angle is small in spite of the fineness of the single yarn, so that the woven fabric with small fluctuation coefficient of the non-interlaced part area, small fluctuation coefficient of EC/V and small deviation is formed.

Comparative example 1

The procedure of example 1 was repeated except that the rate of adhesion of the ionic surfactant in the oil supplying step was changed to 70 ppm. Table 3 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The contact angle of water drops is large, and woven fabrics with large variation coefficient and large deviation of EC/V are formed.

Comparative example 2

The procedure of example 1 was repeated except that the deposition rate of the ionic surfactant in the oil supplying step was changed to 840 ppm. Table 3 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. The contact angle of the water drop is small, and the variation coefficient of EC/V is large, so that the woven fabric with deviation is formed.

Comparative example 3

The winding step was performed in the same manner as in example 1, except that the short-period vibration width ratio B was set to 0.2 and the package width W was set to 8.5 cm. Table 3 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. A woven fabric having a large variation coefficient of the non-woven portion area, a large variation coefficient of EC/V, and a variation is formed.

Comparative example 4

The winding process was performed in the same manner as in example 1, except that the package width W was set to 32 cm. Table 3 below shows the physical properties of the polyamide 66 fiber and the evaluation results of the woven fabric. A woven fabric having a large variation coefficient of the non-woven portion area, a large variation coefficient of EC/V, and a variation is formed.

TABLE 1

TABLE 2

TABLE 3

Industrial applicability

The synthetic fiber for an airbag of the present invention is excellent in water inclusion (instantaneous hydrophilicity of yarn) in weaving using WJL, and thus, significantly improves weft yarn flying property (following property for jet water), and has a uniform non-woven portion area, and thus, is excellent in characteristics of flying uniformly and linearly (uniform flying property of yarn). Due to these two characteristics, the quality of the base fabric in the width direction is not changed, and high-speed weaving is possible. Accordingly, the synthetic fiber for an airbag of the present invention can be suitably used as a yarn for weaving a woven fabric for an airbag, particularly a weft yarn.

Description of the reference numerals

1. Packaging body

2. Paper tube

3. Spinneret nozzle

4. Spinning nozzle tube head

5. Cold air chamber

6. Oil supply device (finishing agent giving device)

7. Traction roller

8. First roller

9. Second roller

10. Third roller

11. Fourth roller

12. Yarn path control guide

13. Interweaving device

14. Coiling machine

15. Single yarn

16. Water drop

W width of wound package

B ratio of short period shaking amplitude

Guide angle for starting theta winding

Alpha drop contact angle

Length of a non-interlaced part

b width of non-interlaced part

Claims

1. A synthetic fiber for an airbag, characterized in that the synthetic fiber is a multifilament synthetic fiber for an airbag having interlacing parts and non-interlacing parts, the contact angle of water drops on the surface of a single yarn is 50-75 DEG, and the variation of the area of the non-interlacing parts per 20cm is 10% or less in CV value.

2. The synthetic fiber for an airbag according to claim 1, wherein the non-woven portion area is 12.5 to 20cm in evaluation per 20cm range in the yarn length direction ² Is not limited in terms of the range of (a).

3. The synthetic fiber for an airbag according to claim 1 or 2, having a single yarn number of 60 to 250.

4. The synthetic fiber for an airbag according to claim 1 or 2, which has a single yarn fineness of 1 to 7dtex.

5. The synthetic fiber for an airbag according to claim 1 or 2, which has a number of single yarns of 200 to 250 and a fineness of 1.0dtex to 1.8dtex.

6. The synthetic fiber for an airbag according to claim 1 or 2, which has an interweaving degree of 10 to 35 pieces/m.

7. The synthetic fiber for an airbag according to claim 1 or 2, wherein the deviation in the longitudinal direction of the contact angle of the water drop on the surface of the single yarn is 5% or less in terms of CV value.

8. The synthetic fiber for an airbag according to claim 1 or 2, wherein the finishing agent adhesion rate is 0.6 to 1.2% by weight.

9. The synthetic fiber for an airbag according to claim 1 or 2, wherein the anionic surfactant containing a phosphorus atom and/or the anionic surfactant containing a sulfur atom is attached at 200 to 500ppm relative to the weight of the fiber.

10. The synthetic fiber for an airbag according to claim 1 or 2, which satisfies the following conditions (1) to (4):

(1) The total fineness is 150-800 dtex;

(2) The strength is 7.5-9 cN/dtex;

(3) The elongation is 15-25%; and

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

11. The wound package of synthetic fibers for airbags according to claim 1 or 2, wherein the width W of the package is 8 to 22cm.

12. A method for producing a synthetic fiber for an airbag, comprising the steps of:

13. The method for producing a synthetic fiber for an airbag according to claim 12, wherein a width W of a package obtained by winding the synthetic fiber into a tube is 8 to 22cm.

14. The method for producing a synthetic fiber for an air bag according to claim 12 or 13, wherein the finishing agent is applied by the finishing agent applying device so that 200 to 500ppm of the anionic surfactant containing a phosphorus atom and/or the anionic surfactant containing a sulfur atom is adhered to the weight of the fiber.

15. The method for producing a synthetic fiber for an air bag according to claim 12 or 13, wherein the finishing agent applying device has 2 or more positions in different positions in the yarn path direction, and at least 2 finishing agent applying devices face each other in the direction of the oil supply portion.

16. A method for producing a woven fabric for an airbag, comprising the steps of:

a process for weaving a woven fabric at a weaving speed of 800rpm or more using the synthetic fiber for an air bag according to claim 1 or 2 as a weft yarn in a water jet loom.