JP2022147171A - Manufacturing method of coated airbag fabric - Google Patents

Abstract

To provide a manufacturing method of an airbag fabric having a relatively low density, which suppresses generation of an ear flare in weaving, suppresses occurrence of wrinkles in a coating step, can give a uniform coatability, and can suppress positional deviation at the time of cutting.SOLUTION: There is provided a manufacturing method of a coated airbag fabric made of synthetic fibers and having a cover factor of 2000 or less, in which a water jet loom equipped with a ring temple is used, the number of increased yarns is 2 or less at the left and right ear parts, and a ratio R of the ear flare amount is 5.0% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing coated airbag fabrics.

In recent years, airbags have been installed to mitigate collisions in automobile accidents. An airbag is a bag-like device that inflates to protect passengers and pedestrians outside the vehicle when a sudden impact is applied to the vehicle due to an external factor. It is

Since airbags are safety components, it is required that product variations do not affect their operation. Therefore, the woven fabric forming the airbag is required to be uniform (uniform in the width direction and longitudinal direction). A high-density fabric such as those commonly used in airbag fabrics, e.g., a plain weave design with a warp and weft of 470 dtex and a warp and weft fabric density of 55 threads per inch (2.54 cm) in both warp and weft; In the case of weaving, the higher the weft density, the greater the amount of movement of the cloth fell before weaving from the most advanced position of the reed to the warp delivery side. As a result, as described in (a) to (d) below, problems are likely to occur during weaving and subsequent steps.

(a) During beating, the woven fabric in the vicinity of the cloth fell causes a bumping phenomenon, making it difficult to obtain a woven fabric with a desired weft density.

(b) After the weft is driven in, the cutter cuts the weft at each of the left and right ends before weaving. The weft crimp is increased, which conversely reduces the warp crimp at the edge of the selvage. Therefore, the warp tension on both selvages is reduced. As a result, the gripping force of the warp on the weft is reduced, and the weaving ends of both selvages before weaving are retracted. As a result, fluff is induced due to warp looseness in the selvage, and stable weaving becomes impossible.

(c) When the rotation speed of the loom is increased, the phenomenon that the weave ends at the edges of the fabric recede more remarkably. Warp slack in the selvage portion of the fabric causes a cloth length difference between the selvage portion and the central portion, resulting in flare (also referred to as "ear lobing") in which the selvage ends are wavy. The airbag fabric is cut and sewn into a bag body, and the cutting pattern is designed to maximize the effective use of the airbag fabric. However, since the edges of the cut product are likely to fray, cutting defects are likely to occur if flare occurs near the edge. As a result, the airbag is misaligned, and the desired shape of the airbag cannot be obtained, and the necessary functions are not provided.

(d) Flare in gray fabric not only impairs processability during roll winding and subsequent scouring and setting processes, but also causes wrinkles. When a resin is coated, the flare not only hinders the processability of the coating process, but also causes uneven coating amount of the coating resin and wrinkles.

As various attempts to prevent the above disadvantages (a) to (d), Patent Documents 1 to 3 describe a technique for preventing ear flare by weaving four or more additional threads on the left and right. It is

However, it is difficult to use bar temples in the weaving of relatively low-density fabrics for airbags in pursuit of light weight. A weaving method for an airbag fabric that can suppress ear flare when ring temples with good weaving properties are used has not been known so far.

JP 2014-181430 A JP 2009-35834 A JP 2019-23377 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a relatively low density airbag fabric with improved processability such as coating and cutability. More specifically, selvedge flare, which tends to occur in the weaving of relatively low-density airbag fabrics using ring temples, is suppressed, and the occurrence of wrinkles during processing such as coating and misalignment during cutting are suppressed. To provide a high-quality airbag fabric capable of

In the present invention, as a result of intensive research to solve the above problems, the cause of ear flare is not only the looseness of the ear, but also the unhung part and distortion inside the ear by hanging the ear. and found that ear flares were induced. Therefore, the present inventors have found that by reducing the number of extra threads used in the selvage portion, the selvage hanging at the selvage end portion can be reduced and the selvage flare can be suppressed.

That is, the present invention provides the following inventions.

A method for producing a coated airbag fabric made of synthetic fibers and having a cover factor of 2000 or less, wherein a water jet loom equipped with a ring temple is used for weaving, and two or less additional yarns are used for each of the left and right selvages, The formula below:

{In the formula, S = ear flare amount (cm ² ), W _k = ear flare width (cm), H _k = ear flare depth (cm), n is the number of ear flares, R is the ear flare amount ratio (%) , F is the base fabric width (cm)}, wherein R is 5.0 or less.

According to the manufacturing method of the coated airbag fabric of the present invention, it is possible to reduce the ear flare even in a fabric having a relatively low density. As a result, wrinkles are suppressed during the scouring, heat setting, and coating processes that are performed after weaving. Textiles can be provided.

FIG. 10 is a schematic diagram for ear flare amount measurement; FIG. 4 is a schematic diagram of triangle S _k when ear flare amount is measured; FIG. 4 is a schematic diagram of using a light when measuring the amount of ear flare.

In the present invention, the selvage flare amount and selvage flare amount ratio are characteristics for evaluating the slackness of the fabric and the waviness of the selvage of the fabric, and are measured by the following procedure (see FIGS. 1, 2 and 3). Pull out a roll sample (original fabric) on a flat table in the longitudinal direction, cut it into 2 m pieces, stack the measurement samples so that a total of 20 sheets are laminated, and place a 3 kg paper tube that fills the width. , rolled in the longitudinal direction without applying force from the ends. A light with an illuminance of 1000 Lx at a distance of 50 cm is used to illuminate from a height of 10 cm upward in order from the tip of the ear, and a triangular shadow due to the ear flare is found. Ear flare width ( _Wk ) is the bulge width in the longitudinal direction of the fabric, and the bulge length in the width direction is the bulge length in the fabric width direction in the ear flare that appears when light is applied obliquely from a position 20 cm away from the center of the raised ear flare in the longitudinal direction. The ear flare depth (H _k ), the ear flare width as the base, and the ear flare depth as the apex, the area of a triangle is measured on all two sides of the fabric with the ear tufts, and the total area is calculated to calculate the ear flare. The amount S was divided by the sample area to calculate the ear flare ratio R.

{Wherein, S = ear flare amount (cm ² ), W _k = ear flare width (cm), H _k = ear flare depth (cm), n is the number of ear flares, R is the ear flare amount ratio (%) , F is the fabric width (cm)}
The ear flare amount ratio of the airbag fabric of the present invention must be 5.0% or less. More preferably, it is 4.5% or less. When the ear flare amount ratio does not exceed 5.0%, it is possible to suppress positional deviation during cutting, particularly during lamination cutting, and to manufacture airbags having normal functions. In addition, the slackness of the selvage is suppressed, and the occurrence of wrinkles during processing and non-uniformity of the coating can be reduced.

[Fabrics for Airbags]
The airbag fabric of the present invention (hereinafter also simply referred to as fabric) is made of synthetic fiber multifilament (hereinafter also referred to as synthetic fiber yarn). Here, the base portion means the portion of the woven fabric body other than the selvage portion. Materials for the synthetic fibers include, for example, polyamide fibers, polyester fibers, aramid fibers, rayon fibers, polysulfone fibers, ultra-high molecular weight polyethylene fibers, and the like. Among them, polyamide-based fibers and polyester-based fibers, which are excellent in mass productivity and economic efficiency, are preferable.

Examples of polyamide fibers include nylon 6, nylon 66, nylon 12, nylon 46, copolymer polyamide of nylon 6 and nylon 66, nylon 6 copolymerized with polyalkylene glycol, dicarboxylic acid, amine, etc. Fibers made of copolyamide or the like can be mentioned. Among them, nylon 6 fiber and nylon 66 fiber are particularly excellent in strength and are preferable.

Examples of polyester fibers include fibers made of polyethylene terephthalate, polybutylene terephthalate, and the like. Fibers made of copolymer polyester obtained by copolymerizing polyethylene terephthalate or polybutylene terephthalate with isophthalic acid, 5-sodium sulfoisophthalic acid, or an aliphatic dicarboxylic acid such as adipic acid as an acid component may also be used.

These synthetic fibers also contain heat stabilizers, antioxidants, light stabilizers, smoothing agents, antistatic agents, plasticizers, Additives such as thickeners, pigments, and flame retardants may also be included. In addition, as the cross-sectional shape of the monofilament of the synthetic fiber, a flat cross-section can be used in addition to the circular cross-section.

The fabric for airbags produced by the present invention usually preferably has the same synthetic fiber yarns as warp and weft. Using the same synthetic fiber yarn as warp and weft means that both warp and weft are made of the same type of polymer, both warp and weft have the same single fiber fineness, and both warp and weft have the same total fineness. Polymers of the same type are polymers having a common main repeating unit, such as nylon 66 and polyethylene terephthalate. For example, a combination of a homopolymer and a copolymer is also preferably used as the same kind of polymer as used in the present invention. Furthermore, if the presence or absence of a copolymerization component, and if copolymerization is used, the same combination of types and amounts of the copolymerization component is used, it is not necessary to distinguish between the warp and the weft, which is preferable in terms of production management.

The synthetic fiber yarn used as the base yarn of the fabric in the present invention is preferably a synthetic fiber filament with a single fiber fineness of 1 to 7 dtex. By setting the single fiber fineness to 7 dtex or less, the voids occupied between the single fibers in the woven fabric are reduced, and the filling effect of the fibers is further improved, which is preferable because the air permeability can be reduced. In addition, when the single fiber fineness is small, the rigidity of the synthetic fiber filament is lowered, and the effect of improving the flexibility of the fabric is also obtained, which is preferable because the storability of the airbag is improved.

The total fineness of the synthetic fiber thread used as the base thread of the woven fabric is preferably 150-600 dtex. By setting the total fineness of the synthetic fiber yarns used as the base yarn to 150 dtex or more, the strength of the woven fabric is maintained. Moreover, by setting the total fineness to 600 dtex or less, it is possible to maintain compactness during storage and low air permeability. The total fineness is more preferably 200-550 dtex, still more preferably 250-500 dtex. By setting the total fineness within this range, it is possible to improve strength, slip resistance, low air permeability, flexibility, and compact storability of the fabric in a well-balanced manner.

The boiling yield of the synthetic fiber yarn used as the base yarn of the woven fabric is preferably 5 to 15%. When the boiling yield of the synthetic fiber yarn used as the base yarn is 5% or less, low air permeability cannot be obtained, and when the boiling yield is 15% or more, the compactness deteriorates Synthetic fibers constituting the woven fabric in the present invention. In particular, the tensile strength of the synthetic fiber yarn used as the base yarn is 8.0 to 9.0 cN/dtex for both warp and weft in order to satisfy the mechanical properties required for airbags and from the viewpoint of yarn production. is preferred, and more preferably 8.3 to 8.7 cN/dtex.

The woven fabric produced in the present invention is composed of warp and weft yarns made of the same synthetic fiber yarns as described above, and the structure of the woven fabric is not particularly limited. Examples of the woven fabric include plain weave, twill weave, satin weave, variations of these weaves, multiaxial weave, and the like. Among these, plain weave fabric is particularly preferable because it has excellent mechanical properties and is thin when used in an airbag. The weave density may vary depending on whether the woven fabric is resin-treated or not, and also depending on the fineness of the weaving yarn. preferable. If the cover factor exceeds 2000, the basis weight of the woven fabric will be large and the fabric will be coarse and hard. When the cover factor is 2000 or less, the woven fabric is suppressed from being rough and stiff, and the coating provides shape stability and air permeability, and the above effects are likely to be achieved. On the other hand, the lower limit of the cover factor is preferably 1700 or more. If the cover factor is less than 1700, the basis weight of the woven fabric tends to be small, and misalignment tends to occur. In addition, if misalignment occurs during coating, only the resin is exposed, resulting in insufficient strength. The cover factor (CF) is a value calculated from the total fineness and weave density of yarns used for the warp or weft, and is defined by the following formula (1).
CF=(Dw×0.9) ^1/2 ×Nw+(Df×0.9) ^1/2 ×Nf (1)
In equation (1), Dw is the warp total fineness (dtex), Nw is the warp density (thread/2.54 cm), Df is the weft total fineness (dtex), and Nf is the weft density (thread /2.54 cm).

[Method for manufacturing fabric for airbag]
In the method of manufacturing an airbag fabric according to the present invention, first, the warp yarns having the total fineness described above in relation to the fabric are warped and placed on a loom. Similarly, the weft threads are placed on the loom. Although the loom is not particularly limited, it is preferable to use a loom equipped with a ring temple device when weaving a low-density airbag fabric. When full-face temples are used, the pushing amount when weft yarn is woven by beating is reduced, and the balance with the winding amount is lost, resulting in variations in density in the width direction of the fabric. In particular, when a fabric with a cover factor of 2000 or less is woven with full-face temples, the amount of weft pressed in by beating is small, so the winding tension of the fabric increases, and the central part of the fabric is stretched, resulting in poor dimensional stability in the width direction. Chipping, unsuitable for airbag fabrics. Examples of looms include water jet looms, air jet looms, rapier looms, and the like. Although the type of loom is not limited, a water jet loom is preferable as the loom because high-speed weaving is relatively easy and productivity can be easily improved.

During weaving, the tension applied to each warp constituting the base portion of the fabric is preferably adjusted in the range of 0.2 to 0.5 cN/dtex. When the warp tension is within the above range, the dimensional stability of the resulting woven fabric can be improved by reducing the inter-filament voids in the bundle of multifilament yarns constituting the woven fabric. If the warp tension is less than 0.2 cN/dtex, the binding force of the weft yarn during weaving is low, and it is difficult to obtain a fabric having the same density between the warp yarn and the weft yarn. On the other hand, when the warp tension exceeds 0.5 cN/dtex, the contact area (adhesion) between the warp and the weft tends to increase in the woven fabric. Therefore, the warp tends to become fuzzy, and the weaving properties tend to deteriorate. A method for adjusting the warp tension is not particularly limited. For example, the warp tension can be adjusted by adjusting the warp let-off speed of the loom, adjusting the weft driving density, or the like. Whether or not the warp tension is within the above range can be confirmed, for example, by measuring the tension applied to each warp between the warp beam and the central portion of the back roller during operation of the loom with a tension measuring instrument.

In the present invention, when fabrics for airbags are weaved, entanglement yarns and additional yarns are used at the ends of the selvages.

The entwining thread is also called a leno, and in order to prevent the selvage from fraying, a plurality of threads are entwined at the outermost edge of the selvage of the fabric and tighten the weft to form the selvage. When forming the ears, generally a planetary gear mechanism is used, more preferably a planetary gear torsion system is used. Other methods of forming the ears may be used. It is preferable that the number of wires to be used is two or more, preferably two, at each end.

The booster thread is also called a stay thread, and is used for the purpose of preventing the selvage of the fabric from fraying, and is arranged between the saddle thread and the warp in the selvage of the fabric to assist the entanglement thread. However, the planetary system is not used for the additional thread. It is preferable to use a plain weave that is excellent in selvage tightening properties. If the number of additional yarns is increased when used, the yarns will shrink at the time of processing, resulting in hangover, so two or fewer yarns are used at each end. If the additional yarn is not used in the present invention, the selvage tightening of the entwining yarn is insufficient and the warp cannot be restrained, resulting in fraying of the selvage. Further, when the number of additional yarns is four or more, the edge fraying does not occur, but the shrinkage at the time of processing causes the warp to shrink more than the warp yarns, causing the edge hanging.

The total fineness of the entwining yarns and the additional yarns used in the woven fabric is preferably 150 dtex or less. If the total fineness is 150 dtex or less, the binding force of the weft per fineness is increased, and the fabric can be constructed without loosening the selvage.

The materials and types of the entanglement thread and the additional thread are appropriately selected according to the type of base thread and the weaving density. In the present invention, although the material is not particularly limited, polyamide-based fibers and polyester-based fibers, which are excellent in mass productivity and economic efficiency, are preferable. The types of fibers are not limited to monofilaments, multifilaments, spun yarns, etc. However, multifilaments and monofilaments are preferred because single yarns of spun yarns are highly likely to cause troubles in guides and healds.

After the weaving is finished, the obtained woven fabric is dried if necessary. The drying temperature is usually 80° C. or higher. When the drying temperature is 80° C. or higher, the woven fabric has a small dry heat shrinkage and improved dimensional stability. As a result, the woven fabric can be suitably used as an airbag.

Next, the woven fabric is appropriately subjected to processing such as scouring and heat setting. The scouring temperature in the scouring process is preferably 30° C. or higher, more preferably 45° C. or higher. By applying heat, the entanglement thread and the additional thread shrink more than the base thread, and the loosening of the selvage can be suppressed. Also, the scouring temperature is preferably 80° C. or lower, more preferably 70° C. or lower. If the scouring temperature is 30° C. or higher, the fabric may be freed of residual strain and have improved dimensional stability. Further, when the scouring temperature is 80° C. or lower, large shrinkage of the fabric is suppressed. As a result, the fabric may have improved dimensional stability.

The heat setting temperature in the heat setting is preferably a temperature capable of removing strain remaining in the woven fabric after weaving and suppressing large shrinkage of the woven fabric, similarly to scouring. Specifically, the heat setting temperature is preferably 110° C. or higher, more preferably 120° C. or higher. Also, the heat setting temperature is preferably 190° C. or lower. When the heat setting temperature is within the above range, the woven fabric obtained can have improved dimensional stability, the entanglement yarn and the increase yarn shrink more than the base yarn, and loose selvage can be suppressed.

The woven fabric that has undergone the above steps may be a coated woven fabric that is appropriately coated with a resin or elastomer. The woven fabric of the present invention can be made non-breathable by being coated. When coating is applied, the amount of coating is preferably about 5 to 35 g/m ² . As the resin or elastomer, those having heat resistance, cold resistance, and flame retardancy are preferred. As the resin or elastomer, for example, silicone resin, polyamide resin, polyurethane resin, fluororesin or the like is preferably used.

As described above, according to the method for manufacturing an airbag fabric of the present invention, it is possible to reduce the selvage flare at the selvage ends during weaving of a relatively low-density airbag fabric. In particular, when used as a fabric for coating airbags (coating base fabric), it has excellent processing passability and uniform application in the scouring, setting, and coating processes after weaving. It is possible to provide an airbag fabric that suppresses the sagging and has excellent bag-manufacturing properties.

EXAMPLES The present invention will be specifically described below with reference to examples. The present invention is by no means limited to these examples. In addition, in the following examples, each characteristic value was calculated by the following method.

<Method for calculating characteristic values>
(total fineness)
The total fineness was calculated by measuring the regular fineness with a predetermined load of 0.045 cN/dtex according to JIS L1013:2010 8.3.1 A method.

(weave density)
The weave density of each warp and weft was calculated based on JIS L 1096:2010 8.6.1. Specifically, the sample was placed on a flat table, unnatural wrinkles and tension were removed, and the number of warp and weft yarns in a 2.54 cm section was counted at five different locations, and the average value of each was calculated.

(tensile strength)
Tensile strength is JIS K 6404-3:19996. Based on test method B (strip method), 5 test pieces were taken in each of the warp and weft directions, and the yarn was removed from both sides to make the width 30 mm. The specimen was pulled at a gripping distance of 150 mm and a tensile speed of 200 mm/min until the specimen was cut, and the maximum load until cutting was measured, and the average value was calculated for each of the warp and weft directions.

(cover factor)
The cover factor (CF) was calculated by the following formula from the density of the fabric and the fineness of the threads forming the fabric.
CF=(Dw×0.9) ^1/2 ×Nw+(Df×0.9) ^1/2 ×Nf (1)
In equation (1), Dw is the warp total fineness (dtex), Nw is the warp density (thread/2.54 cm), Df is the weft total fineness (dtex), and Nf is the weft density (thread /2.54 cm).

(Flare amount ratio)
It was measured by the following procedure. Pull out a roll sample (original fabric) on a flat table in the longitudinal direction, cut it into 2 m pieces, stack the measurement samples so that a total of 20 sheets are laminated, and place a 3 kg paper tube that fills the width. , rolled in the longitudinal direction without applying force from the ends. Using a light with an illuminance of 1000Lx at a distance of 50 cm, illuminate from a height of 10 cm above the edge of the ear in order, find a triangular shadow caused by the ear flare, and place it 20 cm away from the center of the ear flare in the longitudinal direction. Ear flare width ( _Wk : cm) is defined as the bulge width in the longitudinal direction of the fabric in the ear flare that appears when the light is applied obliquely, and ear flare depth ( _Hk : cm) is defined as the bulge in the width direction of the fabric. A triangular area S _k (cm ² ) was calculated by regarding the base as the base and the depth of the ear flare as the vertex. Calculate S _k for all the ear flares on both ears of the fabric, sum them up to the ear flare amount S (cm ² ), and divide by the sample area (base fabric (sample) width F (cm) x 200 (cm)) Then, the ear flare ratio R (%) was calculated.

<Example 1>
(warp, weft)
The warp and weft are made of nylon 66, have a circular cross-sectional shape, are composed of 136 single filaments with a single fiber fineness of 3.5 dtex, a total fineness of 470 dtex, and a tensile strength of 8.5 cN/dtex. A non-twisted synthetic fiber filament having an elongation of 23.5% was prepared.

(weaving)
Using the above yarn as the base yarn for the warp and weft, using a water jet loom equipped with a ring temple, a plain weave with a warp weaving density of 46 / 2.54 cm and a weft weaving density of 46 / 2.54 cm. woven. At that time, the warp tension was adjusted to 0.21 cN/dtex.

At that time, entanglement yarns and additional yarns were used for both selvages of the fabric. As the entanglement thread, a nylon 66 monofilament having a circular cross-sectional shape, 22 detex, a tensile strength of 4.8 cN/dtex, an elongation of 47.5%, and a boiling water shrinkage of 10.5% was used. Two per section were supplied from the planetary system. A 22 dtex nylon 66 monofilament similar to the entanglement thread was used as the booster thread, and two threads were supplied to each selvage from a bobbin.

(scouring and heat setting)
Then, the resulting fabric was scoured at 65°C with an open soap scouring machine, washed with hot water at 40°C, and dried at 120°C. Furthermore, using a pin tenter dryer, the width ratio is set to be the same as the width of the fabric after drying, and the fabric is heat set at 180 ° C. for 60 seconds under a dimensional regulation with an overfeed rate of 1%. did. Table 1 shows the properties of the resulting fabric.

(coating processing)
Next, the fabric is coated with a solventless silicone resin having a viscosity of 50 Pa·s using a floating knife coater so that the surface becomes 15 g/m ² , and then vulcanized at 190°C for 1 minute. An airbag fabric was obtained.

(evaluation)
The resulting woven fabric had a small selvage flare, and the selvage tightness was uniform and good.

<Comparative Example 1>
An airbag fabric was produced in the same manner as in Example 1, except that in the weaving process, 6 additional yarns were provided in each selvage portion, and the width ratio in the scouring and heat setting steps was 0%.

The resulting woven fabric had large selvage flare and uneven selvage tightness. Table 1 shows the properties of the resulting fabric.

<Comparative Example 2>
In the weaving process, the fabric was woven in the same manner as in Example 1 except that the number of additional yarns was set to 0 on both selvages. Selvedge fraying occurred and weaving was impossible.

Wk: ear flare width Hk: ear flare depth S1 to Sk: flare area F: fabric (sample) width

Claims (1)

A method for producing a coated airbag fabric made of synthetic fibers and having a cover factor of 2000 or less, wherein a water jet loom equipped with a ring temple is used for weaving, and two or less additional yarns are used for each of the left and right selvages, The formula below:

{In the formula, S = ear flare amount (cm ² ), W _k = ear flare width (cm), H _k = ear flare depth (cm), n is the number of ear flares, R is the ear flare amount ratio (%) , F is the fabric width (cm)}, wherein R is 5.0% or less.

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