JPH06306731A - Woven polyester filament cloth for air bag - Google Patents

Abstract

PURPOSE:To provide a non-coated woven polyester filament cloth for air bag, free from calendering treatment and having excellent maintenance of air- permeability and burst strength after the storage in dry or humid state at a high temperature for a long period. CONSTITUTION:The objective non-coated and non-calendered woven polyester cloth for air bag is composed of polyester multifilament yarns constituting the warps as well as wefts. The maximum thermal stress of the yarn measured by heating a yarn specimen of 50mm long from the room temperature to the melting point of the yarn under initial load of 0.08g/de at a heating rate of 150 deg.C/min is <=0.8g/de and the maximum thermal shrinkage of the yarn determined under the same heating condition is <=25%. The intrinsic viscosity of the yarn determined in o-chlorophenol at 25 deg.C at a concentration of 1.2g/100ml is 0.80-0.95dl/g and the terminal carboxyl group content is 5-35eq/ton.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyester filament woven fabric for an air bag. More specifically, the present invention has a very low air permeability even after long-term dry heat aging, exhibits excellent burst resistance even when a car or aircraft crashes, and is safe such as protecting the occupants of the car or aircraft from burns. Non-coated for air bags for automobiles and aircraft with excellent properties
To polyester filament fabric.

[0002]

Airbags for automobiles and aircraft are
It is necessary for these to be able to safely protect the occupants in the event of a collision, not to cause a fire due to the inflation gas contained therein, and to have a high burst resistance in the event of a collision.

In order for the air bag not to pose a fire hazard to the occupant, it is necessary to reduce the air permeability of the fabric forming the air bag. Further, in order to enhance the burst resistance of the air bag, it is necessary that the woven fabric has high tensile breaking strength, tensile breaking elongation and burst strength. Canadian Patent 974,745 describes
A non-coated, non-calendered nylon filament fabric for an air bag is disclosed. However, the air bag obtained from the above nylon filament woven fabric has insufficient air permeability and burst strength.
This is because this woven fabric uses a tenter which causes a very large difference in density between the warp yarn and the weft yarn and causes a large residual stress and strain to remain in the woven fabric.

Japanese Unexamined Patent Publication (Kokai) No. 3-137245 discloses a non-coated nylon 66 filament woven fabric which is not subjected to calendaring and can be used for an air bag. This woven fabric, when subjected to scouring and heat setting, has an air permeability measured under 500 pa of 10 l / dm ² / min.
(Lower than about 0.4 ml / cm ² /sec/0.5inchAq). The example of this publication has an air permeability of 3.4 l / dm ² / min.
(About 0.14 ml / cm ² /sec/0.5inchAq) nylon 66 filament woven fabric is disclosed, and the tensile cutting strength is 2,300 to 3,300 N / 5 cm (about 141 to 202).
Kg / 3 cm) fabrics are also disclosed. However, in the above publication, there is no mention of the stability of air bag air permeability and burst strength over a long period of time.

As a typical example of an uncoated polyester filament fabric for an air bag, US Pat.
77,016 (corresponding to JP-A-4-2835)
Non-coated resin having a gas permeability of 0.5 ml / cm ² /sec/0.5 inch Aq or less, which is not coated with or impregnated with resin.
Topolyester filament fabrics are known.

In addition, US Pat. No. 5,010,663
The specification (corresponding to JP-A-4-2835) discloses a non-coated polyester filament woven fabric having an air permeability of 1.5 ml / cm ² /sec/0.5 inch Aq or less. In these specifications, when the polyester filament woven fabric is calendered because the polyester filament has low hygroscopicity, the processed polyester filament woven fabric is compared with the conventional calendered nylon filament woven fabric.
It is specified that the bulk recovery is low and the change in air permeability is small. However, no mention is made of the long-term air permeability stability of the polyester filament woven fabric after dry heat or wet heat aging, and no specific method of increasing the air permeability stability. Moreover, the burst strength and durability of this fabric are not described in these specifications.

In US Pat. No. 4,921,735 (corresponding to JP-A-1-122275), the air permeability is 0.
A non-coated polyester filament woven fabric for an air bag, which has been subjected to calendering of 0.53 ml / cm ² /sec/0.5 inch Aq, is disclosed. However, there is no mention or suggestion of stabilization of the long-term air permeability and burst strength of this fabric after dry heat or wet heat aging, and the teaching of the method.

EP 0,442,373 A1 discloses a non-calendered non-coated polyester filament woven fabric having a tensile elongation at break of 25% even when subjected to scouring and heat setting. Has been done. The example of this European patent specification has an air permeability of 4.7-
9.4 l / dm ² / min (about 0.12-0.23 ml / cm ² / sec /
It is stated that a non-coated polyester filament woven fabric having no calendering of 0.5 inch Aq) was obtained. However, this specification describes dry heat or wet heat.
No mention is made of the long-term breathability and burst strength stability of this fabric after ginning.

When an air bag made of a conventional polyester filament woven fabric is left in a folded state in an automobile or an aircraft for a long period of time, the air bag has a high temperature and a high temperature during that time, for example. After being exposed to the humid atmosphere several times, the air permeability of the air bag is significantly higher than the initial value. This phenomenon occurs in the conventional nylon 66 filament woven air bag. Therefore, when the inflation gas is blown into the old air bag, the amount of the inflation gas leaking out from the air bag is increased and the air bag is inflated. However, the internal pressure of the airbag may not reach the desired value. If the internal pressure of the inflated air bag is not at a sufficiently high level, the passengers in the car or aircraft cannot exhibit a sufficiently high impact absorbing effect, and the passengers will be damaged by the collision. Furthermore, as the amount of inflation gas leaking from the airbag increases, the risk of burns to the occupant's face that hits the airbag during a collision increases. Therefore, air-
It is important that the air permeability of the air bag remains unchanged at a low value even when the bag is dried or moist at a high temperature for a long time.

If the air bag has a low burst strength retention rate and such an air bag has been stored in an automobile or an aircraft for a long time, the air bag will have a low burst strength, and therefore high pressure inflation will be applied to the air bag. May burst. Therefore, even if the air bag is stored at a high temperature in a dry or wet state for a long time, it is necessary that the burst strength of the air bag is maintained at a high level.

As described above, it is possible to provide a non-coat woven fabric for an air bag, which exhibits sufficient stability or durability in terms of air permeability and burst strength even after being stored for a long period of time under severe conditions. It has been sought after for a long time.

[0012]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a calendering process for an air bag which has a long lasting high air permeability and burst strength even after aging at high temperature, dry or wet conditions. It is to provide an uncoated polyester filament fabric.

[0013]

The above object is a fabric for an air bag, both warp and weft of which are made of polyester multifilament yarn, and an initial load of 0.08 g / min at a temperature rising rate of 150 ° C / min. The maximum thermal stress of the yarn determined by heating a yarn piece having a length of 50 mm from room temperature to the melting point of the yarn under de is 0.8 g / de or less, and the maximum of the yarn determined under the same heating conditions. Heat shrinkage is 25
% Or less, the intrinsic viscosity of the yarn measured at a concentration of 1.2 g / 100 ml in orthochlorophenol at a temperature of 25 ° C. is 0.80 to 0.95 dl / g, and the terminal carboxyl group content is 5%. It can be achieved by a polyester filament woven fabric having an uncoated and non-calendered air bag, which is 35 equivalents / ton.

The object of the present invention is to weave warp yarns and weft yarns made of polyester multifilament having a dry heat shrinkage of 3 to 13% at 150 ° C., and the cover factors in the warp direction and the weft direction are both 800 to 1,200. It is a non-coating product produced by dry heat setting by a metal surface contact tension type roll set method with a raw machine having a cover factor difference of 200 or less in the warp direction and the weft direction of 200 or less, preferably 1,000 to 1,200. It can be achieved with untextured polyester filament fabric.

The polyester filament woven fabric of the present invention has a maximum thermal stress of 0.8 g when the warp yarn and the weft yarn constituting the same are heated from room temperature to the melting point of the yarn.
/ De or less, and the maximum heat shrinkage is required to be 25% or less.

The maximum thermal stress of the yarn is determined by the following method.
That is, a thread piece is taken out from an air bag or a woven fabric, cut into a length of 200 mm, fixed at a length of 50 mm with an initial load of 0.08 g / de, and fixed at a rate of 150 ° C./minute. The temperature is raised from room temperature to the melting point of the yarn piece. next,
The maximum heat shrinkage stress of the yarn piece is measured so that the yarn piece does not undergo heat shrinkage. The maximum thermal stress of the yarn piece is expressed by the value of g / de obtained by dividing the measured maximum heat shrinkage stress by the denier value of the yarn piece.

The maximum heat shrinkage rate of the yarn is determined by the following method. That is, a thread piece is taken out from an air bag or a woven fabric and cut into a length of 200 mm, and similarly, a length of 50 mm is applied with an initial load of 0.08 g / de to make it tense, and at a speed of 150 ° C./min. The thread piece is heated from room temperature to the melting point of the thread piece. Next, the maximum thermal shrinkage of the yarn piece is measured while the yarn piece is not fixed.

The maximum thermal stress and the maximum thermal shrinkage of the yarn are
It develops at temperatures in the range of 240-260 ° C.

When the maximum thermal stress of the yarn exceeds 0.8 g / de, the air permeability of the fabric after dry heat aging at 120 ° C. for 500 hours exceeds 0.5 ml / cm ² /sec/0.5 inchAq, which is undesirable. Rise to a level. In an airbag fabric having a high yarn density, the yarns are in strong contact with each other and the movement is restricted. However, in practice, this movement is restricted only to the monofilaments on the yarn surface portions that are in direct contact with each other. Therefore, even if the thermal shrinkage is small, if the thermal stress of the yarn is large, the monofilaments in the portions of the yarn that are not in direct contact with each other can overcome the above constraint and relatively shrink. As a result, the surface portions of the yarns that are in direct contact with each other are made bulky by the monofilaments whose shrinkage is constrained. Due to this phenomenon, the tightness of contact between the yarns in the woven fabric is lowered and the yarns are separated from each other, which is not preferable because the air permeability of the woven fabric is increased. The maximum thermal stress is preferably 0.6 g / de or less, more preferably 0.5 g / de or less.

When the maximum heat shrinkage of the yarn exceeds 25%,
The air permeability of the fabric after dry heat aging at 120 ° C. for 500 hours rises to a level exceeding 0.5 ml / cm ² /sec/0.5 inchAq, which is not preferable. Even if the maximum thermal stress is sufficiently low, if the maximum thermal shrinkage is too large, the single fibers in the yarn portions that are not in direct contact with each other can freely shrink as described above. Therefore, the surface portions of the yarns that are in direct contact with each other become bulky and move away from each other, increasing the air permeability of the fabric. The maximum heat shrinkage is preferably 20% or less, more preferably 18% or less.

Even if the thermal stress of the yarn is low, the thermal contraction rate of the yarn is not always small. Further, even if the heat shrinkage rate of the yarn is small, the thermal stress of the yarn does not always become low. In order for the heat shrinkage of the air bag to exhibit a high degree of stability, both the warp and the weft of the air bag have a maximum thermal stress of 0.8 g / de or less and a maximum heat shrinkage of 25%.
The following and all must be low.

In the polyester filament woven fabric of the present invention, both the warp and the weft made of the polyester multifilament constituting the woven fabric have an intrinsic viscosity of 0.8 to 0.8 measured in orthochlorophenol at 25 ° C. and a concentration of 1.2 g / 100 ml. It is necessary to be 0.95 dl / g.

When the intrinsic viscosity of the yarn is less than 0.8 dl / g, the heat resistance may be insufficient in both dry heat and wet heat. Therefore, the maximum thermal stress and the maximum heat shrinkage ratio of the polyester filament yarn, and The air permeability of the air bag after dry heat aging is increased, which is not preferable, and the burst strength retention rate of the air bag after dry heat aging or wet heat aging is decreased, which is also not preferable.

On the other hand, if the intrinsic viscosity is more than 0.95 dl / g, the filament yarn is not preferable because the mechanical strength may be lowered, and thus the burst strength of the air bag obtained from the filament yarn is low. After all it is not preferable. Intrinsic viscosity of warp and weft is 0.82-0.90d
It is preferable to keep the ratio within the range of 1 / g. A polyester multifilament yarn having an intrinsic viscosity within this range can be produced by appropriately controlling the polymerization conditions and melt spinning conditions.

In the polyester filament woven fabric of the present invention, the warp yarn and the weft yarn made of the polyester multifilament constituting the woven fabric have a terminal carboxyl group content of 5 to 35 equivalents / ton. When the terminal carboxyl group content is less than 5 equivalents / ton, the resulting polyester multifilament yarn may have poor uniformity of fineness and mechanical properties, while the terminal carboxyl group content is 35 equivalents / ton. If it exceeds, the heat resistance of the polyester multifilament yarn may be low in both dry heat and wet heat, the air permeability of the woven fabric increases after dry heat aging, and the burst strength retention rate after dry heat or wet heat aging decreases. However, neither is preferable. The preferred range of the terminal carboxyl group content is 7 to 30 equivalents / ton, and the more preferred range is 10 to 25 equivalents / ton. The terminal carboxyl group content can be adjusted by appropriately controlling the polymerization conditions and melt spinning conditions of the polyester.

Both the warp and the weft polyester filament yarns of the polyester fabric of the present invention preferably have a residual diethylene glycol content of 0.1 to 1.5% by weight. When the residual diethylene glycol content is less than 0.1% by weight, the polyester multifilament yarn has low flexibility, and the burst strength retention rate of the air bag using the same tends to be low. On the other hand, when the residual diethylene glycol content exceeds 1.5% by weight, the polyester multifilament yarn has low heat resistance in both dry heat and wet heat, and the maximum shrinkage ratio is increased, which is not preferable, and the air obtained from this is also preferable. The bag tends to have a higher air permeability after dry heat aging and a lower burst strength retention rate after dry heat or wet heat aging. The residual diethylene glycol content is more preferably 0.2 to 1.
0% by weight, particularly preferably 0.3 to 0.7% by weight
Is. The residual diethylene glycol content of the polyester multifilament yarn can be controlled by appropriately adjusting the polymerization conditions and the melt spinning conditions.

Further, the polyester multifilament yarn constituting the warp and the weft has a titanium oxide content of 0.
It is desirable to control it to 2% by weight or less. If the titanium oxide content exceeds 0.2% by weight, the polyester multifilament yarn may have low heat resistance, in which case the maximum thermal stress will rise, and the air bag obtained from this will have an air permeability after dry heat aging. And the burst strength retention rate decreases. It is more preferable to control the titanium oxide content of the polyester multifilament yarn to 0 to 0.1% by weight.

Further, the polyester multifilament yarn constituting the warp and the weft has a crystallinity of 45 to 50.
It is preferably 65%. When the crystallinity is less than 45%, the woven fabric has insufficient shape retention and low heat resistance,
The air bag obtained from this is not preferable because the air permeability after dry heat aging increases and the burst strength retention rate decreases. On the other hand, when the crystallinity exceeds 65%, the woven fabric may still have a low shape-retaining property, and the air bag obtained from the woven fabric has a decreased flexibility after dry heat aging and an increased air permeability. , Neither is preferable. The crystallinity of the polyester multifilament yarn is more preferably 48 to 63%, particularly preferably 50 to 60%. The crystallinity of the polyester multifilament yarn can be controlled by appropriately adjusting melt spinning conditions, drawing conditions and / or heat setting conditions.

The multifilament yarns constituting the warp and weft of the polyester fabric of the present invention are crystalline (10
0) The crystal size in the direction perpendicular to the lattice network plane is 3.0 to 9.0.
It is preferably nm. The crystal size is 3.0n
When it is less than m, the woven fabric has low shape retention and low heat resistance, and the air bag obtained from the woven fabric tends to have increased air permeability after dry heat aging and a reduced burst strength retention rate. On the other hand, when the crystal size is more than 9.0 nm, the woven fabric tends to have low flexibility and the shape retention tends to be low, and the air bag obtained has an increased air permeability after dry heat aging, which is not preferable. . The crystal size of the polyester multifilament yarn is more preferably 3.5 to 8.5 nm, and particularly preferably 4.0 to 8.0 nm. Crystal of polyester multifilament yarn (10
0) The crystal size in the direction perpendicular to the lattice network plane is the melt spinning condition,
It can be controlled by appropriately controlling the stretching condition and / or the heat setting condition.

Further, the twist coefficient of the polyester multifilament yarn of the warp and weft of the polyester fabric of the present invention is preferably 2,500 or less. The twist coefficient of the filament yarn is defined by the following equation (1). Twist coefficient = (D) ^1/2 × T ··· (1) (In the formula, D is the denier value of the yarn, and T is the number of twists of the yarn expressed in the number of turns / m.)

When the twist coefficient exceeds 2,500, the woven fabric has an increased bulk-restoring property, so that the air bag obtained from the woven fabric has an increased air permeability after dry heat aging. The twist coefficient is more preferably suppressed to 2,000 or less, further preferably 1,500 or less, and particularly preferably 0.

Furthermore, the multifilament yarn constituting the warp and weft of the polyester fabric of the present invention preferably has an interlace number of 10 to 50 per meter. If the number of interlaces is less than 10 / m,
It is difficult to weave, and when the number of interlaces exceeds 50 / m, the bulk recovery of the obtained product increases, so that
The air bag obtained from this is not preferable because the air permeability after dry heat aging increases. The number of interlaces of the polyester multifilament yarn is more preferably controlled to 15 to 45 / m, further preferably 20 to 40 / m.
m.

The fineness of the multifilament yarn is preferably 0.5 to 3.0 denier as the fineness of the single fiber. When the fineness of the single fiber is less than 0.5 denier, the multifilament yarn is likely to be fluffed, which makes it difficult to woven at a high density and obtain an air bag having a sufficiently low air permeability. On the other hand, when the fineness of the single fibers exceeds 3 denier, the woven fabric obtained has an increased bulk restoring property, and the air bag obtained therefrom has an increased air permeability after dry heat aging, which is not preferable. The fineness of the polyester monofilament is 1.
0 to 2.5 denier is more preferable, and 1.2 to 2.2 denier is particularly preferable. Total fineness is 200-60
It is preferably 0 denier, more preferably 220.
~ 450 denier.

The polyester filament woven fabric of the present invention preferably has an air permeability of 0.5 ml / cm ² /sec/0.5 inchAq or less after dry heat aging at 120 ° C. for 500 hours. When the air permeability of the woven fabric exceeds 0.5 ml / cm ² /sec/0.5inchAq, when inflation gas is blown into the obtained air bag to inflate it, the gas pressure inside the inflated air bag decreases rapidly. Therefore, the performance of the air bag is insufficient. In addition, since the amount of inflation gas leaking from the air bag increases, the risk of burning the occupant of the interior space of the automobile or aircraft is contaminated by the fine particles in the leaking inflation gas. The air permeability of the polyester filament fabric of the present invention after dry heat aging at 120 ° C. for 500 hours is 0.4 ml.
It is more preferable that it is less than / cm ² /sec/0.5 inchAq.

In the uncoated, non-calendered polyester filament fabric of the invention for air bags, a diameter of 700 m obtained from the fabric
The outer peripheral portion of the two circular fabrics of m is 670 mm in diameter by which the sewing line is concentric with the circle formed by the circular fabric by the double chain stitching method.
After forming a bag-like product which is sewn and joined so as to form a double circle, the bag-like product is subjected to dry heat aging at 120 ° C. for 500 hours, or after wet heat aging at 85 ° C., 95% RH for 500 hours. From the circular hole having a diameter of about 106 mm provided at the center of one circular woven fabric of the bag-like material, high-pressure air accumulated at a pressure of 40 kg / cm ² G and a volume of 40 liters at room temperature is instantaneously injected. The rupture strength retention rate obtained when the bag-shaped product is ruptured is preferably 70% or more with respect to the burst strength of the bag-shaped product before aging.

The production of an air bag to be subjected to the burst strength test and the measurement of the burst strength of this air bag are carried out by the method described above. 70% burst strength retention of polyester fabric
When it is less than 1, the burst strength of the air bag using the same is reduced when it is stored in an automobile or an aircraft for a long time, and therefore there is a risk of bursting when subjected to high pressure inflation. However, the air bag made from the polyester filament woven fabric of the present invention has extremely high burst strength and stability for a long period of time even under a high temperature dry condition or a high temperature and high humidity condition, which may injure an occupant of an automobile or an aircraft. Can be protected from The burst strength retention of the polyester woven fabric is more preferably 80% or more.

In the present invention, as the polyester,
Polyethylene terephthalate, polybutylene terephthalate, polyhexylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene-1,2-bis- (phenoxy) ethane-4,4'-dicarboxylate, and one or more of the above polymers A copolymer comprising repeating units of, for example, polyethylene terephthalate / isophthalate copolymerized polyester, polybutylene terephthalate / naphthalate copolymerized polyester, polybutylene terephthalate / decanedicarboxylate copolymerized polyester, or the above polyester. And a mixture of two or more kinds of copolymerized polyesters. Among them, polyethylene terephthalate is preferable as the polyester for textiles of the present invention because it has a good balance between mechanical properties and fiber forming properties.

As described above, in the polyester filament woven fabric of the present invention, both the maximum thermal stress and the maximum thermal shrinkage of the polyester multifilament yarn constituting the polyester woven fabric are low,
The air permeability is low even after dry heat aging at 120 ° C. for 500 hours, and a high burst strength retention rate is exhibited even after dry heat or wet heat aging for a long period of time. Therefore, the polyester filament woven fabric can be used for producing an air bag from this, in a non-coated state and without being subjected to calendering.

In the present invention, a polyester multifilament yarn having a dry heat shrinkage ratio at 150 ° C. of 3 to 13% is woven as a warp and a weft, and the cover factors in the warp direction and the weft direction are both 800 to 1. , 2
00, the difference in the cover factor between the warp direction and the weft direction is 2
The present invention provides a polyester filament woven fabric for an air bag, which is not coated and is not subjected to calendering, which is produced by performing dry heat setting by a metal surface contact tension type roll set method using a greige machine of 00 or less. .

The polyester multifilament yarn for warp and weft for obtaining a raw fabric has a dry heat shrinkage ratio at 150 ° C. of 3 to 13%, preferably 3.5 to 12%. The dry heat shrinkage of the warp and weft may be the same as each other,
It may be different. If the dry heat shrinkage ratio is less than 3%, the shrinkage ratio in the scouring step and heat setting step of the obtained green machine is too low, which undesirably increases the air permeability of the fabric after dry heat aging. On the other hand, the dry heat shrinkage is 13
If it exceeds%, the air permeability of the woven fabric becomes uneven, which is not preferable.

The polyester multifilament yarn constituting the warp and the weft has a tensile breaking elongation of preferably 20% or less, more preferably 19% or less. When the tensile cutting elongation exceeds 20%, the heat shrinkage rate in the scouring step is low and unsatisfactory, and the woven fabric has a low tensile cutting elongation, which is not desirable. The tensile breaking strength is preferably 9 g / de or more, more preferably 9.2 g / de or more.

The number of monofilaments constituting the multifilament yarn is preferably 140 to 840, more preferably 160 to 600, and particularly preferably 180 to 400. The total fineness of the warp and weft is preferably 200 to 600 denier, more preferably 250 to 550 denier, and particularly preferably 300 to 500 denier.

The polyester filament woven fabric of the present invention has a greige cover factor of 800 to 1,200, preferably 1,000 to 1,20 in both the warp direction and the weft direction.
It is 0. The difference between the two is 200 or less, preferably as close as possible to each other, and it is more preferable that both are equal to each other.

Cover factor CF _{1 in} the warp direction of the raw machine
Is defined by the following equation (2). CF ₁ = (D ₁ ) ^1/2 × S ₁ (2) (wherein D ₁ is the fineness of the warp expressed in denier,
S ₁ is the warp density of the woven fabric expressed in the number of threads / inch. )

Also, the cover factor CF in the weft direction
Is defined by the following equation (3). CF ₂ = (D ₂ ) ^1/2 × S ₂ (3) (wherein D ₂ is the fineness of the weft yarn expressed in denier value,
S ₂ is the density of the weft of the woven fabric expressed in the number of threads / inch. )

When CF ₁ and / or CF ₂ is less than 800, since the shrinkage of the woven fabric by the dry heat setting is not large enough to fill the gap between the yarns, the air permeability of the woven fabric after the dry heat aging is small. Increases unreasonably. On the other hand, CF ₁
And / or if CF ₂ exceeds 1,200, the fibers are clogged more than necessary and the friction between the yarns is increased, so that uniform shrinkage is less likely to occur in the heat setting step. Has a lower burst strength retention rate after dry heat or wet heat aging. CF ₁ and / or CF ₂ is more preferably 850 to 1,150, particularly preferably 1,000 to 1,200.

In the polyester woven fabric of the present invention, it is desirable that the difference ΔCF between the cover factors CF ₁ and CF _{2 in} the warp direction and the weft direction of the greige is 200 or less. Δ
If the CF exceeds 200, the warp yarns and the weft yarns do not shrink in a well-balanced manner, and unduly large stress remains in the woven fabric. Therefore, the air permeability of the fabric after dry heat aging is increased. Also, the burst strength retention of this woven fabric is lowered by dry heat or wet heat aging. More preferably, ΔCF is 150 or less.

The polyester fabric of the present invention is not limited to a specific woven structure. That is, the fabric of the present invention has 1
1/1 plain weave and 2/2 mat weave are preferred, but 2 /
It may be a 1 or 2/2 twill fabric or a ripstop fabric.

Usually, the most preferred weave design is plain weave, which provides sufficient initial air permeability and sufficient air permeability stability even after being exposed to dry heat or moist heat at elevated temperatures for extended periods of time. .

The polyester filament woven fabric of the present invention has a low air permeability, preferably 0.5 cc, produced by shrinking the woven fabric as described above by a multi-roll type roll surface contact type heat setting system. / cm ² / sec /
It is uncoated with 0.5inchAq or less and has not been calendered.

A common conventional heat-setting method for producing low-permeability fabrics for air bags is, in fact, a tenter-type heat-setting machine such as that described in Canadian Patent 974,745. It is applied to textiles under no tension.

In this heat setting method, a fabric having a sufficiently low air permeability can be produced because the density of warp of the fabric is extremely high and the occurrence of crimp of warp can be significantly suppressed even under no tension. Only in the case of textiles. However, if the warp and weft densities differ greatly, the burst strength retention of the resulting air bag will decrease, and at the same time, if the crimp structure in the weft direction of the fabric changes, the tension applied to the end of the fabric will be Since the crimped structure in the lateral direction of the fabric changes because it does not become zero, the air bag obtained has non-uniform air permeability. If the fabric has such an uneven texture,
Dry heat aging undesirably increases the air permeability of the air bag. In order to obtain a woven fabric having a low air permeability not only before dry heat aging but also after the dry heat aging, it is necessary to reduce the crimped structure of monofilaments of warp and weft as uniformly as possible.

Accordingly, a specific tension is applied in the warp direction which is slightly smaller than the heat shrinkage force generated in the warp direction of the fabric when the fabric is brought into contact with the roll surface of a high temperature heat setting machine under sufficient tension. Then, it is preferable that the polyester filament woven fabric is heat set by a roll surface contact type heat setting machine. The tension generated in the weft direction due to the tension generated in the warp direction and the tension generated in the weft direction due to the contact resistance of the weft to the warp causes the woven fabric to appropriately shrink during heat setting. This shrinkage can prevent the formation of undesirably unduly large and uneven crimped structures, and the fabric thus obtained has stable air permeability and also has a high burst strength retention rate after dry heat or wet heat aging. Get higher

Roll surface contact heat set is at least 2
It is desirable to perform the steps in a low temperature step and a high temperature step, which results in a heat-set fabric with a stable and uniform texture. In a preferable example of the heat setting method, the temperature of the low temperature roll is 130 to 170 ° C. and the temperature of the high temperature roll is 160.
It is ˜220 ° C. and higher than the cold roll. More preferably, the heat setting is performed in three or more steps so that the temperature of the fabric is gradually increased by using a heat setting machine equipped with three or more heating rolls. This heat setting is performed with a heating roll having a surface temperature in the above range at a speed of 5 to 30 m / min for about 10 minutes.
It is preferable to carry out for 180 seconds.

In order to obtain the woven fabric of the present invention, it is desirable that the greige is scoured so that the basis weight of the woven fabric after scouring is increased by 2 to 15%, more preferably 3 to 13%, compared to the greige. It is also desirable to heat-set the greige fabric so that the fabric weight of the woven fabric after heat-setting is increased by 8 to 40%, more preferably 10 to 35%, as compared with that before heat setting. However, if the increase in the basis weight caused by the scouring and heat setting steps is too large, the characteristics of the woven fabric after the processing are not uniform, which is not preferable.

Generally speaking, calendering a conventional woven fabric results in a very low initial air permeability of the resulting woven fabric, so that the calendered fabric is useful for air bags. However, the air permeability of this type of fabric increases to the same extent as the air permeability of the corresponding fabric before calendering due to the restoration of bulk over time. Regarding this phenomenon, it is considered that the texture of the fabric changes over a long period of time, the gap between the yarns in the fabric increases, and the air permeability of the fabric increases. On the other hand, the polyester filament woven fabric of the present invention having the above-described specific performance and woven fabric structure is very stable for a long period of time, so that the air permeability can be stably maintained at a small value.

The polyester filament woven fabric of the present invention has a low air permeability and is stable for a long period of time. Therefore, the polyester filament woven fabric can be used in the non-coated and non-calendered state for producing an air bag from this. That is, the air bag manufactured from the non-coated and non-calendered woven fabric of the present invention has an increased air permeability of the polyester multi-filament yarn which does not shrink due to overcoming the constraint between the yarns constituting the same. And without declining the burst strength retention rate, it can be left in a high temperature automobile or aircraft for a long period of time. Therefore, when the inflation gas is blown into the air bag, the high-pressure inflation gas is maintained in the inflated air bag, the high-temperature inflation gas does not practically leak from the air bag, and the air bag does not burst. It does not happen and can keep the safety of passengers in cars and aircraft.

[0058]

EXAMPLES The present invention will be described in more detail with reference to examples. In the examples, the properties of fibers and woven fabrics and the evaluation of air bags were carried out according to the following methods.

Breathability Breathability meter FX3300 (made by Textest, Switzerland)
Was used to measure 0.5 inch water column pressure (125 pa) with a 100 cm ² orifice.

Maximum thermal stress Thermal stress tester TY manufactured by Kanebo Engineering Co., Ltd.
PE KE-2 was used. After removing the warp and weft from the woven fabric, the initial load of each is 0.08 g on the thermal stress tester.
The maximum thermal stress was measured when the test length was fixed at 50 mm / min and the temperature was raised from room temperature to the melting point of the yarn at 150 ° C./min. The maximum thermal stress developed at 240 to 260 ° C. In addition, the value was a value obtained by dividing the maximum heat shrinkage force including the initial load by the yarn denier.

The thermal stress tester described above was used as well as the maximum heat shrinkage . The initial load is 0.08g without fixing the warp and weft removed from the fabric.
/ De, the test length was set to 50 mm, and the maximum heat shrinkage rate was measured when the temperature was raised from room temperature to the melting point of the yarn at 150 ° C./min. The value was a value obtained by dividing the maximum heat shrinkage length on the chart by the original test length.

An intrinsic viscosity polyester multifilament yarn was used, and an orthochlorophenol solution concentration of this was 1.2 g / 100 ml,
It was measured at 25 ° C.

Terminal carboxyl group content polyester multifilament yarn was dissolved in benzyl alcohol at 190 ° C. for 7.5 minutes to give a concentration of 1.0 g.
/ 100ml solution, add chloroform to this,
Phenol red 0.1% solution as an indicator, 0.1
It was quantified by titration with an N sodium hydroxide benzyl alcohol solution.

The residual diethylene glycol content polyester was decomposed with hydrazine, and the decomposition products were quantified by gas chromatography. Titanium oxide content Using a multifilament yarn, titanium metal was quantified by the fluorescent X-ray method and converted into titanium oxide.

Crystallinity was measured by a density gradient tube method using an n-heptane / carbon tetrachloride mixture. Crystal size The crystal size in the direction perpendicular to the (100) lattice network plane was measured by the wide-angle X-ray diffraction method.

Dry Heat Shrinkage Polyester filament yarn is untwisted at 150 ° C. for 3
After free contraction for 0 minutes, it was calculated by the following formula (4). Dry heat shrinkage (%) = [(L-L0) / L] x 100 ...
.. (4) (In the formula, L represents the length of the yarn before contraction, and L0 represents the length of the yarn after contraction.)

Inflation of the air bag One 50 liter air bag for the driver's seat of an automobile
After performing dry heat aging at 20 ° C for 500 hours, the sample was stored in a module and manufactured by Morton International TYPE4.
Inflation test was carried out at room temperature by mounting a type inflator. The internal pressure at this time was measured with a strain gauge.

Tensile breaking strength (σ) and tensile breaking elongation (ε) of the woven fabric were measured by the woven fabric tensile test method described in JIS L-1096. The fabric width was 3 cm, the test length was 20 cm, and the pulling speed was 20 cm / min.

Preventing Burns in Inflation of Airbags TYP manufactured by Morton International Co., Ltd. in a module containing about 50 liters of air bags for the driver's seat of an automobile.
An E4 type inflator was attached and heated at 95 ° C. for 6 hours or more to immediately carry out inflation. At this time, the gas passage divergence from the surface of the airbag was observed using a high-speed video, and the burn preventive property was evaluated in the following two stages. Good: When there is little white smoke jetting and scattering from the air bag surface Poor: When there is much white smoke jetting and scattering from the air bag surface

Bursting Strength of Air Bag By blowing high-pressure air into an air bag of about 50 liters for the driver's seat of an automobile at high speed, the internal pressure when the air bag bursts was measured, and this was taken as the burst strength. .

Bursting strength retention rate Polyester woven fabric was cut to obtain two circular woven fabrics having a diameter of 70 mm, which were superposed on each other and sewn together at their outer peripheral portions so as to form a double ring having a sewing line of 670 mm in diameter. To produce a bag-like product, and through a circular hole with a diameter of about 106 mm provided in the center of one circular fabric of this bag-like product, high pressure air accumulated at a pressure of 40 kg / cm ² G and a volume of 40 liters at room temperature. Was instantaneously injected to burst the bag, and the burst strength was measured with a strain gauge. The burst strength of the air bag was determined by the pressure at the time of burst. Separately, a bag-like material is prepared by the above-mentioned method, and this is stored at 120 ° C and 0%
Dry heat aging for 500 hours at H, or 85 ° C, 95
% RH, heat aged for 500 hours. In this way
The burst strength of the bagged bag was measured by the same method. The burst strength retention rate of the bag-shaped product was expressed by the ratio (%) of the burst strength of the bag-shaped product subjected to dry heat or wet heat aging to the burst strength of the bag-shaped product.

Example 1 A monofilament fineness of 1.7 denier, a yarn fineness (total fineness) of 420 denier, and a polyethylene terephthalate multifilament yarn having various properties shown in Table 1 were used as warp and weft to produce a flat yarn. A woven fabric (fabric) was created and refined. The scoured woven fabric, 150 ℃ with the first multi-stage heating roll,
Then, two-stage heat setting at 180 ° C. was performed with a second multi-stage heating roll. Table 1 shows the cover factor of the obtained woven fabric.

The air permeability of this woven fabric before and after dry heat aging was as shown in Table 1. Further, an air bag for a driver's seat of a vehicle having a volume of 50 liters was prepared from a fabric not subjected to heat aging. When an inflation test was conducted on this air bag, the internal pressure of inflation was as shown in Table 1.

Table 1 shows the results of grading the polyester woven fabric in the following two stages as a comprehensive evaluation (judgment). Good: Air permeability after dry heat aging is 0.5 ml / cm ² / sec /
In case of 0.5inchAq or less Poor: Air permeability after dry heat aging is 0.5ml / cm ² / sec /
When exceeding 0.5inchAq

[0075]

[Table 1]

Comparative Examples 1 to 5 The same procedure as in Example 1 was carried out except for the following points. As the polyester multifilament yarn, one having the properties shown in Table 2 was used. In addition, except for Comparative Example 2, the temperature was 180 ° C., the pressure was 670 kg / cm, and the speed was 6 m on one side of the woven fabric.
It was calendered at 1 / min. The properties of the resulting heat set fabric are shown in Table 2. Table 2 shows the inflation inner pressure of the air bag made from these fabrics.
The judgment in Table 2 is the result of evaluation similar to Table 1.

[0077]

[Table 2]

Examples 2-14 and 14A High density plain weaves were made in the same manner as in Example 1. However, as the polyester multifilament yarn, those having the characteristics shown in Tables 3 and 4 were used. The scoured and heat set fabric was not calendered. Tables 3 and 4 show various characteristics of the obtained woven fabric and the air bag having a volume of 50 liters prepared from the woven fabric.

In Tables 3 and 4, the comprehensive evaluation results of airbags are classified into the following two stages. Good: Sufficient burn resistance and burst strength of 0.8 kg / cm
^In the case of ² G or more Poor: Insufficient burn prevention and burst strength of 0.8 kg / c
When less than m ² G

[0080]

[Table 3]

[0081]

[Table 4]

Example 15 A multifilament yarn was prepared from polyethylene terephthalate having an intrinsic viscosity of 0.853 dl / g and a terminal carboxyl group content of 17.4 equivalents / ton. 10 twists on this thread
A warp was made by twisting 0 t / m. The weft was untwisted.
From these warp and weft yarns, a high density plain fabric having a warp yarn density of 53.2 / 25.4 mm and a weft yarn density of 53 / 25.4 mm was prepared with a water jet loom. The obtained raw fabric was scoured and then dried at 110 ° C. for 1 minute. The dried woven fabric had a warp density of 54.8 threads / 25.4 mm, a weft density of 53 threads / 25.4 mm, and a basis weight of 216 g / m ² . The dried fabric was heated at 155 ° C. for about 1 minute in a first multi-stage heating roll using a metal cylinder roll heat setting machine,
Then, a two-stage heat setting was performed with a second multi-stage heating roll at 180 ° C. for about 1.5 minutes. The warp density of the obtained fabric is 5
7 threads / 25.4 mm, weft density is 55.8 threads / 25.4
mm and basis weight was 238 g / m ² . The increase in basis weight of the fabric in the drying step was 2.9%, and that in the heat setting step was 13.3%.

The warp yarn and the weft yarn were removed from the woven fabric after the heat setting, and this was subjected to the test. Further, an air bag was prepared from this woven fabric and the burst strength thereof was measured. Furthermore, after aging the air bag under dry heat or wet heat conditions, the burst strength was measured, and the burst strength retention rate of the air bag was obtained from the burst strength of the air bag before and after aging. The above results are shown in Table 5. Further, an air bag having a volume of 50 liters was prepared from the heat-set woven fabric, and its long-term durability was examined and evaluated. The results are also shown in Table 5.

All of Examples 16 to 21 and Comparative Examples 6 to 7 were carried out by the same procedure as in Example 15. However, various properties of the used warp and weft, and the woven fabric were as shown in Tables 5 and 6. Tables 5 and 6 show the results of the durability of the air bag produced from this.

[0085]

[Table 5]

[0086]

[Table 6]

Example 22 A polyethylene terephthalate multifilament yarn having various properties shown in Table 7 was used as a warp yarn and a weft yarn to prepare a high density plain loom using a water jet loom. This greige has a cover factor of 1,080 in the warp direction, 1,060 in the weft direction, and a basis weight of 1.
It was 99 g / m ² . After scouring this raw machine, it was dried at 110 ° C. for 1 minute in a state where tension was applied in the warp direction using a metal roll surface contact type dryer. The fabric weight after drying was 211 g / m ² . The dried woven fabric was heat set in the following three stages by applying tension in the warp direction using a metal roll surface contact heat setting machine. That is, about 155 ° C. for about 1 minute on the first multi-stage heating roll, 165 ° C. for 1 minute on the second multi-stage heating roll, and 180 ° C. for 1.5 minutes on the third multi-stage heating roll. The basis weight of the heat-set fabric was 255 g / m ² . The increase in the basis weight of the fabric was 6% in the drying stage and 28% in the heat setting stage. The air permeability, tensile breaking strength, and tensile breaking elongation of the heat-set fabric were as shown in Table 7.

An air bag having a volume of 50 liters was prepared from this woven fabric. Table 7 shows the burn-preventing property and burst strength obtained by testing this air bag.

In any of Examples 23 to 28 and Comparative Examples 8 to 11, the same procedure as in Example 22 was carried out. However, various properties of the polyester multifilament yarn used, the raw fabric, the woven fabric after drying, the heat-set woven fabric, and the air bag made from them were as shown in Tables 7 and 8.

[0090]

[Table 7]

[0091]

[Table 8]

[0092]

EFFECT OF THE INVENTION The polyester filament woven fabric of the present invention can stably maintain low air permeability and burst strength even after being stored in a dry or wet state at a high temperature, and prevents occupant burns during inflation. Therefore, it can be used as a highly safe fabric for an air bag that is not damaged even in a severe collision.

Claims (13)

[Claims] 1. A fabric for an air bag, the warp and weft of which are both polyester multifilament yarns, and an initial load of 0.08 at a temperature rising rate of 150 ° C./min.
The maximum thermal stress of the yarn obtained by heating a yarn piece having a length of 50 mm from room temperature to the melting point of the yarn under g / de is 0.8 g / de or less, and the yarn obtained under the same heating conditions Has a maximum heat shrinkage of 25% or less, and the intrinsic viscosity of the yarn measured at a temperature of 25 ° C. in orthochlorophenol at a concentration of 1.2 g / 100 ml is 0.80 to 0.95 dl /
g, and the terminal carboxyl group content is 5 to 35 equivalents /
A ton of polyester filament woven fabric that is uncoated for air bags and has not been calendered. 2. The polyester filament woven fabric for an air bag according to claim 1, wherein the polyester filament yarn has a residual diethylene glycol content of 0.1 to 1.5% by weight and a titanium oxide content of 0.2% by weight or less. 3. The airbag according to claim 1, wherein the polyester filament yarn has a crystallinity of 45 to 65% and a crystal size of 3.0 to 9.0 nm in a direction perpendicular to a (100) lattice network plane of the crystal. Polyester filament fabric. 4. A polyester filament yarn having a twist coefficient of 2,500 or less and an interlace number of 10 to 50 / m.
The polyester filament woven fabric for an air bag according to claim 1, which is 5. The polyester filament woven fabric for an air bag according to claim 1, wherein the polyester filament yarn has an individual fineness of 0.5 to 3.0 denier of the single fibers constituting the yarn. 6. The polyester filament woven fabric for an air bag according to claim 1, wherein the woven fabric after dry heat aging at 120 ° C. for 500 hours has an air permeability of 0.5 ml / cm ² /sec/0.5 inchAq or less. 7. A double circle having a diameter of 670 mm which is concentric with a circle formed by the circular woven fabric by a double chain stitching method on the outer peripheral portion of two circular woven fabrics having a diameter of 700 mm obtained from the woven fabric. To form a bag-like object that is sewn and joined as
After the bag-like material is dry heat aged at 120 ° C. for 500 hours or wet heat aged at 85 ° C., 95% RH for 500 hours, a circular hole having a diameter of about 106 mm provided at the center of one circular fabric of the bag-like material. From room temperature, pressure is 40kg / c
The burst strength retention rate obtained when the high-pressure air accumulated in m ² G and a volume of 40 liters was instantaneously injected to rupture the bag-shaped product was higher than the rupture strength of the bag-shaped product before aging. The polyester filament woven fabric for an air bag according to claim 1, wherein both are 70% or more. 8. The dry heat shrinkage ratio at 150 ° C. is 3 to 13.
% Weaving warp and weft consisting of polyester filaments to have a cover factor of 800 to 1,200 both in the warp direction and the weft direction, and a difference in cover factor between the warp direction and the weft direction of 200 or less. Non-coated, non-calendered polyester filament woven fabric for air bags, which is produced by drying and setting with a tension roll set method. 9. The polyester filament woven fabric for an air bag according to claim 8, wherein the polyester filament yarn in greige has a tensile cutting elongation of 20% or less. 10. The polyester filament woven fabric for an air bag according to claim 8, wherein the polyester filament yarn has a residual diethylene glycol content of 0.1 to 1.5% by weight and a titanium oxide content of 0.2% by weight or less. 11. The air bag according to claim 1, wherein the polyester filament yarn has a crystallinity of 45 to 65% and a crystal size of 3.0 to 9.0 nm in a direction perpendicular to a (100) lattice network plane of the crystal. Polyester filament fabric for use. 12. A polyester filament yarn having a twist coefficient of 2,500 or less and an interlace number of 10 to 50 /
The polyester filament woven fabric for an air bag according to claim 8, which is m. 13. The polyester filament woven fabric for an air bag according to claim 8, wherein the polyester filament yarn has an individual fineness of 0.5 to 3.0 denier of the single fibers constituting the yarn.