JPH07329670A - Air bag module - Google Patents

Abstract

PURPOSE:To lower cost, and enhance durability for a long time by forming an air bag out of fabric composed of polyester filaments having specified ultimate viscosity and terminal calboxyl group content, and forming a retainer and/or a base plate out of an electric zinc plated steel plate or a fusion zinc plated steel plate. CONSTITUTION:An air gab A is formed out of fabric where its warp and weft are made out of polyester filament yarn the ultimate viscosity and the terminal calboxyl group content of which are 0.80 to 0.95dl/g and 5 to 4O equivalent weight/ton respectively. And a retainer D and/or a base plate C are made out of an electric zinc plated steel plate P or a fusion zinc plated steel pate P. The strength retention of polyester fabric after 1000 hours in a state that it is in contact with the zinc plated steel plate P under an environment of 50 deg.C and 95%, of PH, is preferably more than 70%. Besides, sewing yarn F is preferably polyester yarn. And bolts G and nuts H to be installed on the retainer D are preferably made out of zinc plated corrosion resistant material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air bag module, and more particularly to an air bag module which can be manufactured at a significantly reduced cost as compared with a conventional air bag module and which is excellent in long-term durability.

[0002]

2. Description of the Related Art As an air bag module, there is known an air bag module having an air bag A, an inflator B, a base plate C and a retainer D as basic components as shown in FIG. Conventionally, as a retainer D material for such an air bag module, a chromate steel plate obtained by press-molding a galvanized steel plate or the like and having a thick film chrome plated is used.

In a retainer for an air bag module using a chromate steel plate, a steel plate P is provided with a zinc plating layer Q as shown in a side sectional view of a punch hole portion for a bolt, and this is subjected to press working. After molding,
Since thick-film chrome plating is performed, iron such as punch holes produced by pressing is exposed. For this reason, plating is also applied to the rust-prone end surface, and the surroundings are covered with the thick film chromate layer R, so rust is less likely to occur, but since many plating steps are performed and plating is performed after pressing, Since complicated processes such as oiling before pressing and washing after pressing are required, the manufacturing cost is very high. On the other hand, electrogalvanized steel sheets or hot-dip galvanized steel sheets can be improved in corrosion resistance and can be added with functions such as fingerprint resistance and lubricity. Therefore, the manufacturing cost of the retainer has been expected to be very small.

However, in the air bag module, while the air bag is housed in the vehicle in a state of being in contact with the retainer using the galvanized steel sheet or the galvanized steel sheet for a long time, the air bag is exposed to high temperature and high humidity. After several summer and rainy seasons, the strength of the woven fabric is reduced at the portion in contact with the retainer, and the airbag ruptures from the contact portion when the airbag is deployed. This is because the iron inside the steel sheet is exposed at the end faces such as punch holes produced during the molding of the retainer, and the iron is easily eluted from this portion into the woven fabric.

Therefore, in order to prevent the reduction of the strength of the woven fabric, the punch holes and the end faces have to be plated with a thick film of chromium. In particular, an air bag module using a nylon fabric is problematic because the decomposition reaction of the polymer main chain is excited by iron and the fabric strength is significantly reduced. Further, the air bag module using the polyester woven fabric is slightly better than the nylon woven fabric, but the decrease in the woven fabric strength is still a problem.

On the other hand, also in the base plate, when the iron is exposed at the punch holes and the end faces, the strength of the fabric is deteriorated. Therefore, as shown in FIG. After that, paint coating is performed (S in FIG. 5 is a paint coating film layer). Therefore, the punch holes and the end faces are not exposed, but there is a problem that the cost is increased.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester air bag module which has a significantly lower manufacturing cost than the conventional one and is excellent in long-term durability.

[0008]

The present invention is an air bag module including at least an air bag, an inflator, a base plate and a retainer, and the air bag has an intrinsic viscosity of 0.80 to 0.95 dl / g.
And air composed of a polyester filament yarn having a terminal carboxyl group content of 5 to 40 equivalents / ton as warps and wefts, and a retainer and / or a base plate made of electrogalvanized steel sheet or hot dip galvanized steel sheet. It is a bag module.

The air bag module of the present invention includes at least an air bag, an inflator, a base plate and a retainer as its constituent members as shown in FIG. As one mode thereof, FIG. 2 shows a side cross-sectional view of the airbag module around the inflator. In FIG. 2, A is the bottom cross side of the airbag, B is an inflator, C is a base plate, D is a retainer, E is an apron, F is a sewing thread, and G is a bolt fixed to the retainer. H indicates a nut, and I indicates a wing portion of the inflator.

Nylon woven fabric is known as a fabric for air bags. However, nylon woven fabric has a very strong hydrophilic property. For this reason, fiber molecules swell and a metal such as iron diffuses in the molecule especially under humid heat conditions. Cheap. Further, the amide bond of nylon is strongly adsorbed to a metal, and as a result, the main chain of the polymer is decomposed and the hydrogen bond between fiber molecules is cleaved, so that the fabric strength is reduced. Therefore, in a module having a retainer or a base plate using an electrogalvanized steel sheet or a hot-dip galvanized steel sheet, the woven fabric strength at the contact portion is greatly deteriorated, and therefore, a polyester woven fabric is used in the present invention.

The warp and weft of the polyester fabric for an air bag must have an intrinsic viscosity of 0.80 to 0.95 dl / g. When the intrinsic viscosity is less than 0.80 dl / g, metals such as iron easily diffuse inside the fabric, and heat resistance and wet heat resistance are deteriorated. As a result, the strength retention of the fabric after contacting with a retainer or base plate using electro-galvanized steel sheet or hot-dip galvanized steel sheet especially after long-term wet heat aging decreases, and rupture occurs at the contact portion with the retainer or base plate during bag deployment. Easier to do. on the other hand,
If it exceeds 0.95 dl / g, the physical properties of the polyester filament yarn deteriorate, and the burst strength of the air bag decreases. The intrinsic viscosity is preferably 0.82 to 0.90 dl / g. A polyester filament yarn having an intrinsic viscosity of 0.80 to 0.95 dl / g can be produced by adjusting the polymerization conditions of polyester.

The polyester filament yarn needs to have a terminal carboxyl group content of 5 to 40 equivalents / ton. When the terminal carboxyl group content is less than 5 equivalents / ton, the uniformity of the polyester filament yarn is reduced, and thus the burst strength before aging is reduced. On the other hand, when it exceeds 40 equivalents / ton, hydrolysis reaction using a metal such as iron as a catalyst is promoted, moisture resistance is significantly lowered, and heat resistance is also lowered. For this reason, the strength retention of the woven fabric after long-term wet heat aging is reduced at the contact portion with the retainer or the base plate, and the woven fabric is likely to burst at the contact portion with the retainer or the base plate when the bag is deployed.
The terminal carboxyl group content is preferably 7 to 38 equivalents / ton, more preferably 10 to 35 equivalents / ton. The terminal carboxyl group content can be adjusted by adjusting the polyester polymerization conditions.

In the present invention, as the air bag,
The shape is not particularly limited, but for example, the bottom cloth arranged around the inflator and the top cloth arranged on the occupant side are both made of circular fabric pieces, and a circular shape in which the circumferential portions thereof are sewn and joined is used. Can be mentioned. The bottom cloth may be reinforced with several aprons E inside and / or outside the airbag, as shown in FIG. 2, for example. The apron is preferably a woven fabric made of polyester, which is the same as the bottom cloth and the top cloth that are the main body of the airbag, and is joined to the bottom cloth around the inflator by sewing as shown in FIG. I hope you are there.

The top cloth, the bottom cloth and the apron constituting the air bag may be coated fabrics, but are preferably uncoated fabrics. Since uncoated fabric is not coated with silicone rubber, it can be easily recycled into carpets, car seats, wall materials, etc. In addition, recycling treatment such as remelting and depolymerization is easy. In an air bag using a coated fabric, it is difficult to separate the coated resin and the fiber, and therefore it is extremely difficult to recycle and use the fiber as pure fiber.

As the sewing thread used for joining the top cloth and the bottom cloth and the bottom cloth and the apron of the air bag, polyester thread is preferable. When the sewing thread is polyester, it is the same material as the fabric for the air bag, and thus it is easy to recycle it for other purposes.
Also, in the recycling process such as remelting and depolymerization,
It is extremely effective because the cost required for the separation and purification of impurities can be significantly reduced.

The intrinsic viscosity of the polyester constituting the sewing thread is 0.80 to 0.9 because it is exactly the same as that of the polyester filament thread constituting the fabric for an air bag.
It is preferably 5 dl / g, and 0.82 to 0.90
More preferably, it is dl / g. The terminal carboxyl group content is also preferably 5 to 40 equivalents / ton, more preferably 7 to 38 equivalents / ton, and particularly preferably 10 to 35 equivalents / ton, for the same reason as in the air bag fabric. Is.

The sewing thread is preferably a so-called non-bonded thread which is not impregnated with resin. Non-bonded yarn can be easily recycled together with top cloth, bottom cloth, apron, etc.

In the present invention, the polyester woven fabric is in a state in which an electrogalvanized steel sheet or a hot-dip galvanized steel sheet is in contact with one surface of the polyester woven fabric under an environment of 50 ° C. and 95% RH.
It is preferable that the strength retention rate after holding for 000 hours is 70% or more. When the strength retention rate under this condition is less than 70%, the wet heat stability or durability when mounted in a vehicle and used for a long time is insufficient.

In the present invention, examples of the polyester constituting the air bag fabric and the sewing thread include polyethylene terephthalate, polybutylene terephthalate, polyhexylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene-1,2.
In addition to -bis (phenoxy) ethane-4,4'-dicarboxylate and the like, copolymerized polyesters such as polyethylene isophthalate, polybutylene terephthalate / naphthalate, polybutylene terephthalate / decane dicarboxylate and the like can be mentioned. Among them, polyethylene terephthalate, which has a good balance of mechanical properties and fiber forming properties, is particularly preferable.

The polyester fabric for an air bag of the present invention is woven through the usual weaving process using the polyester filament yarn having the above-mentioned characteristics as a warp and a weft, and the obtained raw fabric is sewn as it is or after it is scoured. It can be manufactured by performing the set. Since the scouring step can wash the spinning oil and the weaving oil, it is preferable to carry out the refining step from the viewpoint of long-term reliability and flame retardancy as an air bag, but it may be omitted for the purpose of cost reduction.

The shrinkage set has a roll surface temperature of 130-
10-40 by multi-stage roll set method at 220 ℃
It is preferable to carry out at a unit weight shrinkage ratio of%. Compared with the tenter set method, the roll set method is superior in flatness of the woven selvages after setting, and does not apply uneven tension by pin or clip gripping in the weft direction. A woven fabric with excellent burst strength when an air bag is created, because it can evenly express elongation and has excellent flatness so that no marks of pins and clips are left so that uniform processing can be performed when performing calendaring. Can be obtained.

Further, the roll set system is preferably a multi-stage system. Since it is a multi-stage type, the shrinking process can be performed mainly in the front stage roll and the setting process in the rear stage roll continuously and uniformly, so that the properties of the woven fabric after the set are uniform, and therefore the burst strength as an air bag is also increased. Excellent fabrics are obtained.

The woven fabric tension in the roll-setting method is greater than the heat shrinkage force generated in the woven fabric warp direction at the roll surface temperature when the woven fabric warp direction is completely fixed,
It is preferable to perform tension setting by applying a slightly lower tensile tension in the warp direction of the fabric. Due to the tensile tension in the warp direction and the tensile force due to the contact resistance in the weft direction, the woven fabric undergoes controlled tension in all directions, while exhibiting an amount of shrinkage commensurate with the dry heat shrinkage. As a result, it is possible to manufacture a woven fabric having a uniform background and a large tensile cutting elongation.

In the roll set, by performing at least two steps of low temperature and high temperature, uniform and good shrinkage can be expressed, and a woven fabric excellent in burst strength can be obtained. More preferably, a low temperature roll of 130 to 170 ° C. and 160
It is a two-stage process of a high-temperature roll at 220 ° C., and a method of gradually shrinking and setting from three temperatures to three stages is most preferable. However, a multi-stage roll set system with a constant temperature may be adopted for the purpose of cost reduction. The processing speed of the shrinkage set is preferably 5 to 50 m / min. Below 5 m / min,
The processing cost increases. On the other hand, if it exceeds 50 m / min, uniform shrinkage cannot be set, and the burst strength as an air bag decreases.

In the present invention, the electrogalvanized steel sheet and hot-dip galvanized steel sheet forming the retainer and / or the base plate are subjected to chromate treatment after electrogalvanizing or hot-dip galvanizing the steel sheet to obtain the corrosion resistance of the conventional product. It is an improved steel plate. The electrogalvanized steel sheet is a steel sheet that has been electroplated in a plating tank, and the amount of zinc adhered is about 45 g / m ² or less per side. Hot-dip galvanized steel sheet is a steel sheet that is plated by immersing it in a hot-dip galvanized bath.
The zinc adhesion amount is about 45 to 120 g / m ^{2 on} one side. These plated steel sheets can be provided with various functions such as fingerprint resistance, lubricity, paintability, and electrical insulation by forming various films on the plated layer.

Retainer and / or used in the present invention
Alternatively, FIG. 3 shows a side sectional view of the punch hole portion of the base plate. In FIG. 3, P is a steel plate, Q is an electrogalvanized layer or a hot-dip galvanized layer, R is a chromate film layer, and T is a film layer such as a lubricating film or an anti-fingerprint film. The side where the end face is curved at the punch hole portion is the drive side of the molding press.

In the present invention, since the bolts and nuts attached to the retainer also come into contact with the air bag, they are preferably galvanized and corrosion resistant members.

[0028]

The polyester woven fabric of the present invention has the intrinsic viscosity and the terminal carboxyl group content adjusted to appropriate values. Therefore, an air bag using this polyester fabric can maintain its strength even when placed in contact with a retainer and / or a base plate made of electrogalvanized steel sheet or hot-dip galvanized steel sheet, and the obtained air bag module is Excellent durability. Further, the retainer and / or the base plate using the electrogalvanized steel sheet or the hot-dip galvanized steel sheet of the present invention can be manufactured at a significantly lower cost than conventional products.

[0029]

EXAMPLES The present invention will be described in more detail with reference to examples. In addition, the measurement of the physical properties of the woven fabrics in the examples was performed according to the following methods.

The woven fabric was drawn from the limiting viscosity fabric, and this was drawn at a concentration of 1.2 g / 100 ml.
-Measured at 25 ° C using chlorophenol solution.

Terminal Carboxyl Group Content The yarn drawn from the fabric was exposed to benzyl alcohol at 215 ° C.
After dissolving for 3 minutes, chloroform was added, and titrated with 0.1N caustic soda benzyl alcohol solution for quantification using phenol red 0.1% solution as an indicator.

Aging Conditions Assuming that the air bag module will be used in a vehicle for a long period of time, one side of the air bag fabric is brought into contact with each of the following steel plates I to V, and a temperature of 50 is applied under a load of about 800 g. It was kept for 1,000 hours under the conditions of ° C and humidity of 95% RH.

The steel plates used are shown below. Steel plate I: An electrogalvanized steel plate obtained by subjecting a steel plate to electrogalvanization and then chrome treatment. It is a steel sheet having a zinc adhesion amount of 40 to 50 g / m ² and a chrome adhesion amount of 20 mg / m ² . Steel plate II: A hot-dip galvanized steel plate obtained by subjecting a steel plate to hot dip galvanizing and then chrome treatment. It is a steel plate having a zinc adhesion amount of 120 g / m ² and a chrome adhesion amount of 15 mg / m ² .

Steel plate III: Steel plate I is an electrogalvanized steel plate with a resin coating. An electrogalvanized steel sheet coated with an organic resin film for improving fingerprint resistance. Steel plate IV: An electrogalvanized steel plate obtained by applying a resin film to Steel plate I. It is an electrogalvanized steel sheet coated with a lubricating resin film for improving lubricity.

Steel plate V: A steel plate (chromate steel plate) plated with thick film chrome used in a conventional retainer. Thick film chrome plating is also applied to the punch holes. In addition, on each steel plate, punch holes having a diameter of 10 mm were formed at several positions, assuming punch holes for a retainer and a base plate.

Textile Strength Tensile strength and single tongue tear strength were measured according to the general textile test method described in JIS L-1096.

Good strength retention rate judgment : When the fabric strength retention rate after aging is 70% or more for both tensile strength and tear strength. Poor: The woven fabric strength retention after aging is less than 70% in at least one of tensile strength and tear strength.

Comprehensive evaluation (general evaluation) Good: When the physical properties of the fabric are judged to be good and the module cost is small. Poor: When the judgment of the physical properties of the fabric is bad or the module cost is high.

Example 1 A high density plain loom was produced using a water jet loom with 420 denier / 250 filaments of polyethylene terephthalate (PET) filament yarn as the warp and weft yarns. After scouring and drying this raw machine, using a metal cylinder roll heat setting machine, a two-stage set of 1st multi-stage heating roll at 155 ° C for about 1 minute and then 2nd heating roll at 180 ° C for about 1.5 minutes And then
A polyester woven fabric having the properties shown in Table 1 was obtained. With one side of this polyester fabric in contact with the steel plate I,
After aging under the aging conditions, the fabric strength was measured, the strength retention rate was calculated, and these were evaluated (determined). In addition, a comprehensive evaluation was performed including the module cost when this polyester fabric was used for an air bag and a steel plate was used for a retainer and / or a base plate. The results are shown in Table 1.

Examples 2 to 4 A polyester woven fabric was woven in the same manner as in Example 1 and the shrinkage setting conditions were changed to obtain the polyester woven fabrics shown in Table 1. It evaluated using the steel plate. The results are shown in Table 1.

[0041]

[Table 1]

In the same manner as in Example 1 except that nylon 66 woven fabric was used in place of the polyester woven fabric, the steel plates shown in Table 2 were contacted for aging, and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0043]

[Table 2]

Comparative Examples 6 to 9 The polyester woven fabrics shown in Table 3 were evaluated in the same manner as in Example 1 with respect to the strength retention and the module using the steel sheet shown in Table 3. The results are shown in Table 3.

[0045]

[Table 3]

[0046]

According to the present invention, it is possible to obtain an air bag module which is significantly lower in cost than conventional products.
Further, this airbag module has excellent long-term stability.

[Brief description of drawings]

FIG. 1 is an abbreviated sectional side view of a peripheral portion of an inflator showing constituent members of an airbag module of the present invention.

FIG. 2 is an abbreviated sectional side view of an inflator peripheral portion showing an embodiment of the present invention.

FIG. 3 is a side sectional view of a punch hole portion of a retainer and / or a base plate of the airbag module of the present invention.

FIG. 4 is a side sectional view of a punch hole portion of a conventional retainer made of a steel plate.

FIG. 5 is a side sectional view of a punch hole portion of a base plate made of a conventional steel plate.

[Explanation of symbols]

 A Air bag B Inflator C Base plate D Retainer P Steel plate Q Electrogalvanized layer or hot-dip galvanized layer R Chromate film layer T Lubricating film, anti-fingerprint film, etc.

Claims (4)

[Claims] 1. In an airbag module including at least an airbag, an inflator, a base plate and a retainer, the airbag has an intrinsic viscosity of 0.
Polyester filament yarn having a terminal carboxyl group content of 80 to 0.95 dl / g and a terminal carboxyl group content of 5 to 40 equivalents / ton, which is formed of a polyester woven fabric as a warp and a weft, and a retainer and / or a base plate are electrogalvanized steel sheets. Or an air bag module made of hot dip galvanized steel sheet. 2. The air bag module according to claim 1, wherein the air bag is sewn with a polyester sewing thread. 3. A polyester sewing thread has an intrinsic viscosity of 0.8.
The airbag module according to claim 2, wherein the terminal carboxyl group content is 0 to 0.95 dl / g and the terminal carboxyl group content is 5 to 40 equivalents / ton. 4. A polyester woven fabric having a strength retention of 70 after being held in an environment of 50 ° C. and 95% RH for 1,000 hours in a state where an electrogalvanized steel plate or a hot-dip galvanized steel plate is in contact with one side of the polyester woven fabric. The airbag module according to claim 1, which is at least%.