JPH1076895A - Fabric for non-coat air bag with improved flatness of ear part of fabric and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent flat property of an ear part of fabrics by manufacturing non-coat fabrics by using polyester filament yarn having the average length of undulation of the ear part of the textiles below specific dimension and a ratio of the average height of undulation to the average length below a specific value. SOLUTION: The average length LM of undulation of an ear part of fabrics must be 30mm or less, and a ratio of the LM value to the average height AM of undulation AM/LM must be 0.2 or less. If the LM value exceeds 30mm, when calendaring is applied or, for example, when shrinking treatment is done by using a roller setter, such problems that loosening is likely to occur in the ear part of the fabrics and a loose part is caught into a roller occur in a roller on a rear step side during shrinking treatment or a winding roller after the shrinking treatment is done. Moreover, if the AM/LM value exceeds 0.2, the uniformity of the ear part of the fabrics is reduced markedly because the average height of undulation is too large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fabric for non-coated airbags and a method for producing the same. More particularly, the present invention relates to a woven fabric for a non-coated airbag, in which the undulation of the woven fabric ear portion is particularly suppressed, and a method for producing the same.

[0002]

2. Description of the Related Art An airbag is required to sufficiently protect an occupant from an impact in a vehicle accident.
That is, the airbag is required not to rupture itself in inflation at any collision. For this reason, airbag fabrics are required to exhibit high burst strength, and in recent years, accidents such as facial abrasions and bruises caused by airbags have been reported, and it is necessary to minimize the impact on the human body. Have been.

[0003] Further, if the scatter of the physical properties of the fabric is large when the airbag is manufactured, the bursting strength of the airbag is reduced, so that it is required to have uniform physical properties. Regarding this uniformity, the woven rim in the weaving process (here, the woven rim means a portion having a length of up to 5% from the end of the woven fabric in the weft direction based on the entire width of the woven fabric. ), Shrinkage wrinkles and the like in the heat shrinking step occur, and the portion used as a woven fabric is the remaining portion after cutting the ears. Was left alone.

Further, with respect to impacts on the human body, particularly with respect to facial abrasions, the surface smoothness and flexibility of the airbag are important, and to achieve this, there have been proposed those which have been subjected to calendar processing. Calendar processing is a processing method in which a woven fabric is compressed by a heated elastic roller and a metal roller to smooth the surface. In addition, since the thickness of the fabric is reduced, flexibility is also provided.

[0005] In the above-mentioned calendering, the fabric is sandwiched between the two rollers, and if the fabric before processing is wrinkled or loose, the loosened portion is caught between the rollers during processing, causing a problem that the roller is damaged. Therefore, the fabric before calendering is required to be flat. The flatness of this woven fabric includes the flatness of the whole woven fabric, especially undulations and wrinkles at the ears, and the flatness of minute parts such as surface irregularities due to the bending (warp, weft) of the filaments that make up the woven fabric. There are two types of sex. Of these, the flatness affects the uniformity and processability of the fabric properties,
The flatness of the air bag as a facial abrasion, etc.
Since the impact on the human body at the time of vehicle collision is low (hereinafter, sometimes referred to as low impact property) and the like, the airbag fabric is required to have both flatness.

A typical example of a conventional airbag fabric is disclosed in Canadian Patent No. 974,745. The woven fabric is obtained by heat shrinking a greige machine made of nylon or polyester for an air bag without tension by a tenter processing method. The fabric is measured at a pressure of 5 lb / inch ² and is 160 cfm or less (about 0.3 cc). / Cm
² / at 125 Pa or less). However, in this method, the warp density of the greige is very large compared to the weft density, and therefore, the greige having a large difference in density between the warp and the weft is thermally contracted under tension without tension by the tenter process. Lack of uniformity of physical properties in the vertical direction.

Also, the airbag fabric disclosed in Japanese Patent Application Laid-Open Nos. 7-90747 and 7-90746 is obtained by heating and shrinking a greige fabric woven at high density. There is no description about a specific mode of the heat shrinking treatment, but only a treatment temperature.

[0008] In each of the prior arts described above, a fabric for an air bag excellent in flatness particularly at the fabric ear has not been obtained.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fabric for an air bag which has an excellent flatness of a fabric ear and cannot be solved by the above-mentioned prior art, and a method of manufacturing the same. is there.

[0010]

Means for Solving the Problems In view of the above prior art, the present inventors have conducted intensive studies on shrinkage processing, particularly in the production of airbag fabrics, and have completed the present invention.

That is, according to the present invention, there is provided a nonwoven fabric for a non-coated airbag comprising a polyester filament yarn, which satisfies the following requirement (a):
It is possible to provide a non-coated airbag fabric having improved flatness of the fabric ear.

(A) Average length LM of the undulation of the fabric ear
The value is 30 mm or less, and the AM / LM value, which is the ratio of the LM value to the average height AM value of the undulation, is 0.2 or less.

According to the present invention, there is further provided a method for producing a woven fabric for a non-coated airbag, comprising shrinking a greige made of polyester filament yarn while passing through a dry heat shrinkage treatment zone. The shrinkage treatment is carried out at a raised temperature along with a positive average temperature gradient of 1 to 20 ° C. per 1 m in the length direction of the greige, and the flatness of the fabric ear is improved. The present invention also provides a method for producing a woven fabric for a non-coated airbag.

In the woven fabric for an air bag of the present invention, the average length LM of the undulation of the woven fabric edge is 30 mm or less, and the ratio of the LM value to the average height AM of the undulation is AM. / LM value needs to be 0.2 or less. Here, to explain with reference to the drawings, in FIG. 1, a solid line indicates an ear portion of an airbag fabric in which undulation occurs in the fabric ear portion, and a broken line indicates an ideal state of the ear portion of the airbag fabric. Squeezed. Here, the dashed line takes several vertices (convex portion B and concave portion C) of the undulation, and, of those vertexes, the thickness of the convex portion having the maximum height and the concave portion having the maximum depth. It is indicated by a vertical bisector bisecting the length of the direction (line segment B′C ′ in FIG. 1). Here, L is obtained from the distance between two adjacent vertices when the dashed line and the solid line overlap on a point. On the other hand, A is the length between the two adjacent vertices where the vertical distance between the broken line and the solid line is maximum. This, LM
If the value exceeds 30 mm, when performing the calendering process, or, for example, in the case of performing a shrinking process by a roller setter, at a subsequent roller during the shrinking process, or a winding roller after the shrinking process In this case, there is a problem that the fabric ear is easily loosened, and the loosened portion is caught in the roller. Also, AM /
If the LM value exceeds 0.2, the average height of the undulations is too large, so that the uniformity of the fabric ears is significantly reduced, and the range that can be used as a fabric for an air bag is reduced.

In the present invention, the crimp rate of the filament yarn constituting the woven fabric, represented by the difference between the tensile elongation of the woven fabric and the tensile elongation of the drawn yarn, is such that the crimp rate of the warp is 12 to 22% and the crimp rate of the weft is Is preferably 5 to 12%.

If the crimp rate of the warp is less than 12% or the crimp rate of the weft is less than 5%, the density of the woven fabric is small, and the cover factor of the woven fabric is too small, so that the burst strength as an airbag is reduced. descend.
Further, since the air permeability becomes too large, it is not preferable as a fabric for a non-coated airbag.

On the other hand, if the crimp rate of the warp exceeds 22% or the crimp rate of the weft exceeds 12%, the thickness of the woven fabric becomes large, so that the storage property such as low impact property and storage property is particularly high. Be impaired.

In the present invention, the amount of the oil agent adhering to the synthetic fiber filament raw yarn used when weaving the fabric for an air bag is preferably 0.3 to 1.0 wt% based on the weight of the fiber. When the amount is less than 0.3 wt%, the frictional resistance of the yarn is too high at the time of yarn production, and single yarn breakage is likely to occur. For example, when weaving in a water jet loom, an oil agent from the original yarn is used. Because fluffing increases even by falling off, it is not possible to obtain a uniform fabric,
Burst strength when sewn as an airbag decreases.
On the other hand, if it exceeds 1.0 wt%, problems such as poor unwinding of the yarn in the weaving process will occur, and the oil agent will not drop off sufficiently during weaving, resulting in poor flame retardancy of the airbag.
Not preferred.

In the present invention, the total amount of residual oil agent on the surface of the airbag fabric is preferably 0.03 to 0.20 wt%. If the residual oil agent adhesion amount is less than 0.03% by weight, problems such as generation of fluff during weaving and adhesion of dust due to static electricity during processing occur, and a high coefficient of friction between fibers constituting the woven fabric. , The tear strength decreases. On the other hand, when the content exceeds 0.20 wt%, the flame retardancy deteriorates, which is not preferable.

In the woven fabric for an air bag of the present invention, the unwound single yarn fineness of the woven fabric is 1.0 to 1.0 for both the warp and the weft.
It is preferably 2.5 de. If the fineness of the drawn single yarn is less than 1.0 de, the weaving property is reduced, so that the burst strength as an airbag is reduced. On the other hand, if it exceeds 2.5 de, the woven fabric becomes coarse and stiff, resulting in poor storability, such as storability and low impact resistance. Further, since the air permeability increases, it is not suitable as a fabric for a non-coated air bag. The unwound single yarn fineness of the woven fabric is more preferably 1.2 to 2.3 de,
1.5 to 2.1 de is most preferred.

The airbag fabric of the present invention must be made of polyester filament yarn. The woven fabric composed of polyester filaments has superior morphological stability compared to nylon 66 woven fabric and nylon 6 woven fabric, and changes in air permeability are small even when left for a long period of time. In addition, since the polyester polymer has no hydrogen bond in its molecular chain, the woven fabric made of polyester is easily creased and easily folded, so that it is easily stored in the airbag module. Further, since the polyester does not have a hydrogen bond in its molecular chain, it has high flexibility, and thus has excellent storage properties and low impact properties.

The woven fabric for an air bag of the present invention is preferably made of a polyester filament yarn having an intrinsic viscosity of 0.80 to 0.95 de / g. 0.8 intrinsic viscosity
If it is less than 0 de / g, the thread pulling strength is insufficient, and the burst strength as an airbag is reduced. The intrinsic viscosity is 0.95d
If it exceeds e / g, the spinning properties will decrease and the variability in the physical properties of the fabric will increase. Intrinsic viscosity is 0.82-0.90de / g
Is more preferred.

As the polyester polymer constituting the polyester filament, for example, polyethylene terephthalate, polybutylene terephthalate, polyhexylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene-1,2-bis (phenoxy) ethane-4,4 In addition to '-dicarboxylate and the like, copolymerized polyesters such as polyethylene isophthalate, polybutylene terephthalate / naphthalate, polybutylene terephthalate / decanedicarboxylate and the like can be mentioned. Among them, polyethylene terephthalate having a good balance between mechanical properties and fiber forming properties is particularly preferred.

In the production method of the present invention, when a green fabric made of polyester filament yarn is subjected to a shrinking treatment while passing through a dry heat shrinkage treatment zone, the green fabric is heated at a raised temperature along the traveling direction of the green fabric. It is necessary to perform a shrinkage treatment while applying a positive average temperature gradient of 1 to 20 ° C. per 1 m in the length direction. Here, the average temperature gradient is
The length obtained by dividing the temperature difference between the exit side and the entrance side of the shrinkage treatment zone by the length of the greige passing through the dry heat shrinkage treatment zone (hereinafter, may be simply abbreviated as the passage length).

If the average temperature gradient is less than 1 ° C./m, the temperature distribution in the shrinkage treatment zone becomes substantially uniform. If the temperature near the entrance of the shrinkage treatment machine is too low, sufficient heat shrinkage cannot be obtained. Conversely, if the temperature near the entrance is set high to obtain sufficient thermal shrinkage, the fabric will rapidly shrink and wrinkles will occur.

On the other hand, the above positive average temperature gradient is 20 ° C. /
If it exceeds m, the rate of temperature rise in the heating zone near the entrance is too high, and the fabric is rapidly shrunk, so that wrinkles are generated.
A preferred positive average temperature gradient is 5 to 15 ° C / m.

Further, it is preferable that the temperature near the entrance of the shrinkage treatment zone is not lower than room temperature and lower than 130 ° C. If the temperature is lower than room temperature, it requires labor for cooling the fabric,
On the other hand, when the temperature is lower than 130 ° C., the shrinkage tends to occur rapidly, which is not preferable. On the other hand, the temperature near the outlet of the shrink treatment zone is preferably set to 170 ° C. or more and less than 240 ° C.
If the temperature is lower than 170 ° C., it is difficult to sufficiently perform the shrinkage treatment on the greige, and if it exceeds 240 ° C., the melting point of the polyester becomes close to the melting point, which is not preferable.

Although it is particularly preferred that the average temperature gradient changes continuously, for example, even when the heating zone is composed of several discontinuous temperature layers, the step of changing the temperature is the same as that of the fabric. What is necessary is just to have an average temperature gradient of 1 to 20 ° C./m in the length direction.

Here, the continuous average temperature gradient means that when the entire shrinkage treatment zone is divided into about 3 to 5 sections in the traveling direction of the greige machine, the difference in average temperature between adjacent sections is 1
It means that it is not less than 20 ° C and not less than 20 ° C.

In the present invention, as a method of forming a specific average temperature gradient, for example, the temperature of hot air supplied into the shrinkage treatment zone is kept constant, and as the hot air blows toward the outlet of the shrinkage treatment zone, the hot air blow-off port A method of giving a temperature difference as a whole in the shrinkage treatment zone, keeping the amount of hot air supplied in the zone constant, and proceeding to the shrinkage treatment zone outlet, as the hot air blows out, A method of increasing the temperature can be used,
In particular, when a roller set method is used, the temperature of the heat medium supplied into each metal roller can be increased as it proceeds to the shrink processing zone outlet, so that a more continuous average in the shrink processing zone. This is preferable because a temperature gradient can be formed.

Compared with the tenter set method, the roller set method has an excellent flatness especially at the woven fabric edge after the contraction setting, and a large initial tension in the weft direction because a non-uniform tensile tension is not applied by gripping pins or clips in the weft direction. That tensile elongation and tensile cut elongation can be expressed uniformly.
Since the flatness is excellent and no trace of pins or clips remains, it is preferable because the bursting strength of the airbag is increased because, for example, uniform processing can be performed when performing calendar processing.

The fabric tension in the roller set system is as follows:
When the fabric warp direction is completely fixed, it is necessary to perform tension setting by applying a slightly lower tensile force in the fabric warp direction than the heat shrinkage force generated in the fabric warp direction at the roller surface temperature. .

Due to the tensile tension in the warp direction and the tensile resistance due to the contact resistance in the weft direction, the woven fabric undergoes a tensile contraction in all directions while exhibiting shrinkage in an amount corresponding to the dry heat shrinkage. As a result, a woven fabric having a uniform initial tensile elongation in both the warp direction and the weft direction can be manufactured. It is most preferable that the contraction setting process by the roller set method is performed by a multi-stage metal roller setter.

In the production method of the present invention, it is preferable that the final basis weight shrinkage of the woven fabric is 10 to 40%. If the areal shrinkage is less than 10%, the tensile toughness of the woven fabric is insufficient, so that the burst strength as an airbag is reduced. vice versa,
If it exceeds 40%, the basis weight increases and the low impact property and high-speed deployability of the airbag deteriorate.

[0035]

[Action and Effect] The reason why the fabric for an air bag of the present invention has such properties is considered as follows. That is, in order to obtain sufficient shrinkage, it is necessary to set at a high temperature. However, during the shrinkage processing at a high temperature, a sharp shrinkage occurs, so that the fabric is easily wrinkled and the flatness of the fabric is deteriorated. I do.
In addition, even if the high-temperature setting is performed after the preliminary setting is performed at a low temperature, wrinkles particularly at the woven fabric ears cannot be suppressed, and the processing cost is undesirably increased.

Here, if the shrinkage treatment zone has a positive average temperature gradient within a specific range with respect to the traveling direction of the greige, the greige gradually shrinks in the ear, so that A nonwoven fabric for a non-coated airbag is obtained in which wrinkles are less likely to occur and the flatness of the fabric ear is improved. In addition, if the zone length is the same, the total amount of heat received by the woven fabric increases, so that sufficient shrinkage can be obtained, processing can be performed in a short time, and productivity can be improved, so that processing cost is reduced.

Therefore, according to the present invention, it is possible to provide an inexpensive fabric for an air bag having excellent flatness of the fabric ear.

[0038]

The present invention will be described below in detail with reference to examples. In addition, each value in an Example was measured according to the following method, respectively.

(1) Weight per unit area: Measurement was performed in accordance with JIS L1096.

(2) Total yarn fineness: Measured according to JIS L1096.

(3) Single thread fineness of thread removal: JIS L1096
The measurement was carried out according to.

(4) Fabric elongation: Measured in accordance with JIS L1096.

(5) Thread elongation: Measured in accordance with JIS L1096.

(6) Crimp ratio: A woven fabric as a sample for measuring the elongation of a woven fabric, and a sample yarn having a drawn elongation taken from a portion adjacent to the sample portion, and the tensile elongation of each sample is measured. The crimp rate was calculated by the following equation. In the measurement, the fabric was measured at 5 points and the yarn was removed at 20 points in the warp direction and the weft direction, respectively, and the average value was shown.

[0045]

(Crimping rate) = (Elongation of woven fabric) − (Elongation of thread removal) (7) Flatness evaluation of woven fabric edge: As shown in FIG.
With the woven fabric of 2 m length spread on a flat table, the width L (mm) and height A (mm) of the undulation at the end are measured at 20 points each from a large object, and the average values LM and AM are measured. Calculated. As conditions for determination, LM ≦ 30 (mm) and AM
/LM≦0.2 was evaluated as good.

(8) Adhesive amount of residual oil agent on woven fabric: 10 g of woven fabric
Was measured by Soxhlet extraction method using 200 g of cyclohexane. The extraction amount based on the absolute dry weight of the woven fabric was defined as the remaining oil agent adhesion amount (wt%).

Example 1 A 420-denier / 249-filament polyester filament yarn (manufactured by Teijin Limited) shown in Table 1 was prepared and woven in a plain weave in a water jet room in a non-twisted state. I got

The greige was subjected to a shrinking treatment by a torque motor type multi-stage metal roller setting machine while applying tension in the warp direction and substantially without tension in the weft direction without wet scouring. The condition of the processing is pass length 1
8m, the temperature near the entrance of the shrinkage treatment zone is 100 ° C,
The physical properties of the fabric were measured with an average temperature gradient of + 7 ° C / m and a processing time of about 1 minute. Table 1 shows the results.

[Examples 2-3 and Comparative Examples 1-4]
Example 1 Example 1 was repeated except that the polyester filament yarn (manufactured by Teijin Limited, manufactured by Hoechst Celanese) and nylon 66 filament yarn (manufactured by Akzo) shown in Table 1 were used instead of the polyester filament yarn used in Example 1. And the physical properties of the fabric were measured in the same manner as in Example 1. The results are shown in Table 1.

[0050]

[Table 1]

[Brief description of the drawings]

FIG. 1 shows a state where an ear portion of a fabric for an airbag is observed from a weft direction in order to explain a value of a swell length L and a value of a swell height A specified in the present invention. It is a schematic diagram.

[Explanation of symbols] A: The height of the undulation of the fabric ear. L · · · The length of the undulation of the fabric ear. B: The top (convex) of the undulation of the fabric ear. B ': Maximum swell height (convex portion). C: The top (recess) of the undulation of the fabric ear. C ': Maximum undulation depth (recess).

Claims (5)

[Claims] A nonwoven fabric for non-coated airbags comprising a polyester filament yarn, characterized by satisfying the following requirement (a), wherein the nonwoven fabric for noncoated airbags has an improved flatness at the edge of the woven fabric. (A) The average length LM value of the undulation of the fabric ear is 30 mm
And an AM / LM value, which is a ratio between the LM value and the average swell height AM value, is 0.2 or less. 2. A method for producing a fabric for a non-coated airbag, comprising shrinking a greige made of polyester filament yarn while passing the greige through a dry heat shrinkage treatment zone, wherein the temperature of the greige is increased along the traveling direction of the greige. A nonwoven fabric for a non-coated airbag with improved flatness at the fabric ears, wherein the fabric is subjected to a shrinkage treatment at a temperature of 1 to 20 ° C. per 1 m in the length direction of the greige, while giving a positive average temperature gradient. Manufacturing method. 3. The method according to claim 2, wherein the temperature on the inlet side of the dry heat shrinkage treatment zone is in the range of room temperature to 130 ° C., and the temperature on the outlet side of the zone is in the range of 170 ° C. to 240 ° C. Production method. 4. The method for producing a non-coated airbag fabric according to claim 2, wherein the shrinking treatment is performed by a multi-stage metal roller setter constituted by a multi-stage metal roller group. 5. The method for producing a non-coated airbag fabric according to claim 2, wherein the fabric is subjected to a shrinkage treatment so that the final basis weight shrinkage is in the range of 10 to 40%.